Configuration reference: Apache and nginx directives

Q: Where is the mod_pagespeed configuration file?

Apache reads `pagespeed.conf` from `/etc/apache2/mods-available/` (Debian, Ubuntu) or `/etc/httpd/conf.d/` (RHEL, AlmaLinux, Rocky); nginx reads `pagespeed` directives from `nginx.conf`, in the `http`, `server` or `location` block; IIS reads `pagespeed.config` from the site root or `%ProgramData%\We-Amp\PageSpeed\`.

Q: What is the minimal working configuration?

On Apache, `ModPagespeed on` and a writable `ModPagespeedFileCachePath`; the packaged `pagespeed.conf` already sets both. On nginx, `load_module modules/ngx_pagespeed_module.so;`, `pagespeed on;` and `pagespeed FileCachePath /var/cache/ngx_pagespeed;` in the server block, plus the three location blocks that let the module serve its own resources. On IIS, `pagespeed on` in `pagespeed.config`.

Q: How do I write the same directive for Apache, nginx and IIS?

Prefix the directive name with `ModPagespeed` on Apache (`ModPagespeedEnableFilters rewrite_images`); on nginx write `pagespeed` followed by the name and a semicolon (`pagespeed EnableFilters rewrite_images;`); on IIS use the nginx form without the semicolon in `pagespeed.config`.

Q: How do I turn mod_pagespeed off for one path?

Scope the switch: `ModPagespeed off` inside a ` ` or ` ` block on Apache, `pagespeed off;` inside a `location` block on nginx, or a `Disallow` directive for a URL wildcard on any server.

Last updated 8 October 2026 Edit this page View as Markdown

Every mod_pagespeed 2.1 directive for the native Apache and nginx module, generated from the source: syntax, default, context and description.

mod_pagespeed is configured with directives in the web server’s own configuration. This page lists every one of them, generated from the module’s source so the list is the list the shipped module accepts: for each directive the syntax on Apache and nginx, the default, the contexts it may appear in and the module’s own description, grouped by area. It starts with where the configuration lives and the smallest configuration that works.

Where the configuration lives

nginx has no separate file: pagespeed directives go into nginx.conf (or a file it includes) in the http, server or location block. The package auto-enables the module’s load_module line on a stock nginx; every directive is written as pagespeed Name value;.

The package drops pagespeed.conf into /etc/apache2/mods-available/ (Debian, Ubuntu) or /etc/httpd/conf.d/ (RHEL, AlmaLinux, Rocky) and loads the module. Edit that file, or put directives in a virtual host, a <Directory> or <Location> block, or .htaccess; every directive is written as ModPagespeedName value.

The installer registers the module and reads pagespeed.config, a flat text file with one directive per line, from the website root (site-level) and from %ProgramData%\We-Amp\PageSpeed\pagespeed.config (server-level); site-level settings override server-level ones. If pagespeed.config is not found the module falls back to iiswebspeed.config, the filename of IISpeed installs. Directives are written as pagespeed Name value without a semicolon; the ModPagespeed and iispeed prefixes are accepted for compatibility. See IIS configuration for match rules and the file format.

Minimal working configuration

load_module modules/ngx_pagespeed_module.so;   # Enterprise Linux: /usr/lib64/nginx/modules/ngx_pagespeed_module.so

http {
    server {
        pagespeed on;
        pagespeed FileCachePath /var/cache/ngx_pagespeed;

        # Let the module serve its own resources.
        location ~ "\.pagespeed\.([a-z]\.)?[a-z]{2}\.[^.]{10}\.[^.]+" {
            add_header "" "";
        }
        location ~ "^/pagespeed_static/" { }
        location ~ "^/ngx_pagespeed_beacon$" { }
    }
}

ModPagespeed on
ModPagespeedFileCachePath /var/cache/mod_pagespeed/

The packaged pagespeed.conf already contains both, so a fresh install optimizes with RewriteLevel CoreFilters without any edit.

pagespeed on

With that in place the module runs the CoreFilters set. Everything below is optional: pick a different rewrite level, add or remove filters, and tune the directives of the area you care about. To see which filters your own pages would benefit from, run them through a PageSpeed Insights test.

How to read the reference

Syntax shows the Apache spelling (ModPagespeedName …) and the nginx spelling (pagespeed Name …;). IIS uses the nginx spelling without the semicolon. Placeholders: on|off is a boolean (true/false also work), number an integer, value a string, wildcard a URL pattern with *.
Default is the value compiled into the module; (empty) means unset, and — that the directive has no value of its own.
Context lists where the directive may appear. On Apache: the server config, a <VirtualHost>, a <Directory>/<Location> block, .htaccess. On nginx: the http, server and location blocks. “Also per request” marks the options that can also be set on a single request with a PageSpeed… query parameter or header.
Platform appears when a directive exists on one server only. An option whose block says the source carries no help text is accepted by nginx but is not registered as an Apache directive.
A since version is not shown: the module source does not record the release a directive first appeared in. Additions are listed per release in the release notes.

The nginx versions each shape runs on are in one table on the worker and reverse-proxy page.

Module states

The module switch, pagespeed / ModPagespeed, takes three states:

State	Behavior
`on`	Full optimization. The module rewrites HTML and serves optimized resources.
`standby`	Serves previously optimized `.pagespeed.` resources and responds to query-parameter requests, but does not optimize new traffic. Use this to drain optimized resources before fully disabling the module.
`unplugged`	Fully disabled. The module does not intercept any requests. This state can only be set at the top level or within a virtual host block, not in directory-level configuration.

pagespeed standby;

On nginx, pagespeed off; is an alias for unplugged.

ModPagespeed standby

pagespeed standby

Scoping directives

Directives can be scoped to parts of a site; a value set at a higher level is inherited by the blocks inside it. The scoping mechanisms differ per server.

Apache supports configuration at several levels:

pagespeed.conf — Global defaults that apply to all virtual hosts.
<VirtualHost> — Per-site overrides.
<Directory> and <Location> — Target specific filesystem paths or URL paths.
.htaccess — Per-directory configuration placed in the document root or subdirectories.

.htaccess configuration is re-read on every request, which adds per-request overhead. For high-traffic sites, prefer <Directory> or <Location> blocks in the server configuration.

<Location /images/>
    ModPagespeedDisableFilters convert_jpeg_to_webp
</Location>

In nginx, use server and location blocks to scope directives:

server {
    pagespeed on;

    location /static/ {
        pagespeed off;
    }
}

Directives set in a server block apply to all locations within that server unless overridden by a more specific location block. Directives whose context is http only are global and are rejected elsewhere.

See IIS configuration for IIS path- and hostname-based scoping.

Virtual hosts

Each virtual host can carry its own mod_pagespeed configuration. Directives set at the global level serve as defaults; virtual host configuration overrides them.

One requirement: HTML pages and the optimized resources they reference must share the same configuration options. If a virtual host serves HTML that references resources optimized under a different set of options, the resources may not be found or may be re-optimized unnecessarily.

server {
    server_name site-a.example.com;
    pagespeed on;
    pagespeed EnableFilters rewrite_images;
}

server {
    server_name site-b.example.com;
    pagespeed on;
    pagespeed EnableFilters collapse_whitespace;
}

<VirtualHost *:80>
    ServerName site-a.example.com
    ModPagespeed on
    ModPagespeedEnableFilters rewrite_images
</VirtualHost>

<VirtualHost *:80>
    ServerName site-b.example.com
    ModPagespeed on
    ModPagespeedEnableFilters collapse_whitespace
</VirtualHost>

Place a pagespeed.config file in each website’s root directory. Each file can carry its own set of directives:

Site A (C:\inetpub\site-a\pagespeed.config):

pagespeed on
pagespeed EnableFilters rewrite_images

Site B (C:\inetpub\site-b\pagespeed.config):

pagespeed on
pagespeed EnableFilters collapse_whitespace

Alternatively, use match rules in the server-level config to scope directives by hostname:

hostname: ^site-a\.example\.com$
pagespeed EnableFilters rewrite_images

hostname: ^site-b\.example\.com$
pagespeed EnableFilters collapse_whitespace

Directive reference

Every directive the module registers, generated from the source at the release the source pin names, grouped by area. Since v1.15.0+r18 configuration validation is strict: out-of-range values for bounded options (image quality levels, progressive JPEG scan counts, HttpCacheCompressionLevel, RewriteRandomDropPercentage) fail configuration load instead of being silently accepted, an invalid filter name in ?PageSpeedFilters= rejects the whole query, and directive matching is case-consistent. A configuration that loaded on an earlier revision may need its values corrected when upgrading.

Areas: Enabling and filter selection (13) · Request handling and policy (33) · In-place resource optimization (14) · Domains and URLs (26) · Optimizer worker (4) · Bot authentication and licensing (19) · Statistics, console and logging (31) · Images (42) · CSS (9) · JavaScript (10) · Caching (46) · Fetching and origins (19) · HTML rewriting and page hints (11) · Threads and limits (2) · Experiments and analytics (11) · Deprecated and ignored (28).

Enabling and filter selection

Allow, DisableFilters, Disallow, EnableAggressiveRewritersForMobile, EnableFilters, EnableRewriting, ForbidAllDisabledFilters, ForbidFilters, ModPagespeed, RewriteDeadlinePerFlushMs, RewriteLevel, RewriteRandomDropPercentage, RewriteUncacheableResources

Allow

Syntax: ModPagespeedAllow wildcard (Apache) · pagespeed Allow wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allows optimization of resources whose URL matches the wildcard. Later Allow and Disallow directives override earlier ones.

DisableFilters

Syntax: ModPagespeedDisableFilters filter[,filter...] (Apache) · pagespeed DisableFilters filter[,filter...]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Comma-separated list of disabled filters

See Filter selection.

Disallow

Syntax: ModPagespeedDisallow wildcard (Apache) · pagespeed Disallow wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Excludes resources (and pages) whose URL matches the wildcard from optimization.

The thin nginx module’s pagespeed_disallow is the equivalent for the Docker and reverse-proxy shape; see Worker and reverse-proxy configuration.

EnableAggressiveRewritersForMobile

Syntax: ModPagespeedEnableAggressiveRewritersForMobile on|off (Apache) · pagespeed EnableAggressiveRewritersForMobile on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allows defer_javascript and defer_iframe for mobile browsers

EnableFilters

Syntax: ModPagespeedEnableFilters filter[,filter...] (Apache) · pagespeed EnableFilters filter[,filter...]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Comma-separated list of enabled filters

The filter names are on the filters reference. See Filter selection for scoping and interaction with RewriteLevel.

EnableRewriting

Syntax: pagespeed EnableRewriting on|off|unplugged|standby; (nginx)
Default: on
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ForbidAllDisabledFilters

Syntax: ModPagespeedForbidAllDisabledFilters on|off (Apache) · pagespeed ForbidAllDisabledFilters on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Prevents the use of disabled filters

See Filter selection.

ForbidFilters

Syntax: ModPagespeedForbidFilters filter[,filter...] (Apache) · pagespeed ForbidFilters filter[,filter...]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Comma-separated list of forbidden filters

A forbidden filter cannot be re-enabled by a more specific scope or by a query parameter. See Filter selection.

pagespeed / ModPagespeed

Syntax: ModPagespeed on|off|unplugged|standby (Apache) · pagespeed on|off|unplugged|standby; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The module switch. on optimizes; standby serves already-optimized .pagespeed. resources and answers query-parameter requests but optimizes no new traffic; unplugged intercepts nothing (on nginx, off is an alias for unplugged). unplugged can only be set at the top level or in a virtual host. nginx needs an explicit pagespeed on; in the server block.

RewriteDeadlinePerFlushMs

Syntax: ModPagespeedRewriteDeadlinePerFlushMs number (Apache) · pagespeed RewriteDeadlinePerFlushMs number; (nginx)
Default: 10
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Time to wait for resource optimization (per flush window) beforefalling back to the original resource for the request.

RewriteLevel

Syntax: ModPagespeedRewriteLevel CoreFilters|PassThrough|OptimizeForBandwidth|MobilizeFilters|TestingCoreFilters|AllFilters (Apache) · pagespeed RewriteLevel CoreFilters|PassThrough|OptimizeForBandwidth|MobilizeFilters|TestingCoreFilters|AllFilters; (nginx)
Default: PassThrough
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Base level of rewriting (PassThrough, CoreFilters)

The baseline filter set. CoreFilters is the production default most sites start from; PassThrough runs only the filters you enable by name; OptimizeForBandwidth optimizes resources in place without rewriting URLs; AllFilters switches on every filter outside the dangerous set, including the opt-in AVIF filters. MobilizeFilters and TestingCoreFilters exist for the project’s own testing. See Filter selection.

RewriteRandomDropPercentage

Syntax: ModPagespeedRewriteRandomDropPercentage number (Apache) · pagespeed RewriteRandomDropPercentage number; (nginx)
Default: 0
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The percentage of time that pagespeed should randomly drop an opportunity to optimize an image. The value should be an integer between 0 and 100 inclusive.

RewriteUncacheableResources

Syntax: ModPagespeedRewriteUncacheableResources on|off (Apache) · pagespeed RewriteUncacheableResources on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Allow optimization of uncacheable resources in the in-place rewriting mode.

Request handling and policy

AcceptInvalidSignatures, AccessControlAllowOrigins, AddOptionsToUrls, AddResourceHeader, AgentOptimize, AllowLoggingUrlsInLogRecord, AllowOptionsToBeSetByCookies, CombineAcrossPaths, DisableBackgroundFetchesForBots, DisableRewriteOnNoTransform, ExperimentalProxyAllRequests, ForceBuffering, HideRefererUsingMeta, HonorCsp, InlineResourcesWithoutExplicitAuthorization, ModifyCachingHeaders, ObliviousPagespeedUrls, OptionCookiesDurationMs, PreserveSubresourceHints, ProxyAuth, RejectBlacklisted, RejectBlacklistedStatusCode, RequestOptionOverride, RespectVary, RespectXForwardedProto, ServeStaleIfFetchError, ServeStaleWhileRevalidateThresholdSec, ServeXhrAccessControlHeaders, StickyQueryParameters, SupportNoScriptEnabled, TrackOriginalContentLength, UrlSigningKey, XHeaderValue

AcceptInvalidSignatures

Syntax: ModPagespeedAcceptInvalidSignatures on|off (Apache) · pagespeed AcceptInvalidSignatures on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Accept resources with invalid signatures.

AccessControlAllowOrigins

Syntax: ModPagespeedAccessControlAllowOrigins value (Apache) · pagespeed AccessControlAllowOrigins value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Comma separated list of origins that are allowed to make cross-origin requests

AddOptionsToUrls

Syntax: ModPagespeedAddOptionsToUrls on|off (Apache) · pagespeed AddOptionsToUrls on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Add query-params with configuration adjustments to rewritten URLs.

AddResourceHeader

Syntax: ModPagespeedAddResourceHeader name value (Apache) · pagespeed AddResourceHeader name value; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Adds a custom HTTP header to every optimized resource the module serves. Repeatable, up to 20 headers.

Repeatable: specify it once per header, up to 20. Since v1.15.0+r18 the limit is enforced exactly.

ModPagespeedAddResourceHeader "X-Custom" "value"

pagespeed AddResourceHeader "X-Custom" "value";

AgentOptimize

Syntax: ModPagespeedAgentOptimize on|off (Apache) · pagespeed AgentOptimize on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Recognize Accept: text/markdown agent requests and add Vary: Accept on HTML. This flag is the only gate: no license or entitlement check sits behind it. 1.1 always serves optimized HTML (no markdown render).

AllowLoggingUrlsInLogRecord

Syntax: pagespeed AllowLoggingUrlsInLogRecord on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

AllowOptionsToBeSetByCookies

Syntax: ModPagespeedAllowOptionsToBeSetByCookies on|off (Apache) · pagespeed AllowOptionsToBeSetByCookies on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow options to be set by cookies in addition to query parameters and request headers.

CombineAcrossPaths

Syntax: ModPagespeedCombineAcrossPaths on|off (Apache) · pagespeed CombineAcrossPaths on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow combining resources from different paths

DisableBackgroundFetchesForBots

Syntax: ModPagespeedDisableBackgroundFetchesForBots on|off (Apache) · pagespeed DisableBackgroundFetchesForBots on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Disable pre-emptive background fetches on bot requests.

DisableRewriteOnNoTransform

Syntax: ModPagespeedDisableRewriteOnNoTransform on|off (Apache) · pagespeed DisableRewriteOnNoTransform on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If false, resource is rewritten even if no-transform header is set

When enabled, resources served with Cache-Control: no-transform are left alone.

ExperimentalProxyAllRequests

Syntax: ModPagespeedExperimentalProxyAllRequests on|off (Apache)
Default: off
Context: Apache: server config, virtual host
Platform: Apache only

Experimental mode where mod_pagespeed acts entirely as a proxy, and doesn’t attempt to work with any local serving.

ForceBuffering

Syntax: ModPagespeedForceBuffering on|off (Apache)
Default: off
Context: Apache: server config, virtual host
Platform: Apache only

Force buffering of non-html fetch responses rather than streaming

HideRefererUsingMeta

Syntax: ModPagespeedHideRefererUsingMeta on|off (Apache) · pagespeed HideRefererUsingMeta on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Hides the referer by adding meta tag to the HTML

HonorCsp

Syntax: ModPagespeedHonorCsp on|off (Apache) · pagespeed HonorCsp on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Controls whether PageSpeed should pay attention to Content-Security-Policy directives

Enabled by default. The module reads Content-Security-Policy response headers and meta tags and suppresses optimizations the policy would block, such as inlining resources or injecting scripts. Set it to off to optimize without consulting CSP, and verify pages that rely on strict policies. Since v1.15.0+r18 the filters that inject inline scripts also back off cleanly when the policy disallows inline script.

InlineResourcesWithoutExplicitAuthorization

Syntax: ModPagespeedInlineResourcesWithoutExplicitAuthorization value (Apache) · pagespeed InlineResourcesWithoutExplicitAuthorization value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Specifies the resource types that can be inlined into HTML even if they do not belong to explicitly authorized domains.

ModifyCachingHeaders

Syntax: ModPagespeedModifyCachingHeaders on|off (Apache) · pagespeed ModifyCachingHeaders on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Set to false to disallow mod_pagespeed from editing HTML Cache-Control headers. This is not safe in general and can cause the incorrect versions of HTML to be served to users.

Controls whether the module sets caching headers on HTML responses. Do not disable it unless you fully understand the interaction with downstream caches: disabling it can cause stale optimized content to be served.

ObliviousPagespeedUrls

Syntax: pagespeed ObliviousPagespeedUrls on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

OptionCookiesDurationMs

Syntax: ModPagespeedOptionCookiesDurationMs number (Apache) · pagespeed OptionCookiesDurationMs number; (nginx)
Default: 600000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The max-age in ms of cookies that set PageSpeed options.

PreserveSubresourceHints

Syntax: ModPagespeedPreserveSubresourceHints on|off (Apache) · pagespeed PreserveSubresourceHints on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Keep original subresource hints in place.

ProxyAuth

Syntax: ModPagespeedProxyAuth value (Apache)
Default: (empty)
Context: Apache: server config, virtual host
Platform: Apache only

CookieName[=Value][

] — checks proxy requests for CookieName. If CookieValue is specified, checks for that. If Redirect is specified, a failure results in a redirection to that URL otherwise a 403 is generated.

RejectBlacklisted

Syntax: pagespeed RejectBlacklisted on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

RejectBlacklistedStatusCode

Syntax: pagespeed RejectBlacklistedStatusCode number; (nginx)
Default: 403
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

RequestOptionOverride

Syntax: ModPagespeedRequestOptionOverride value (Apache) · pagespeed RequestOptionOverride value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Token passed in URL to enable pagespeed options in params.

RespectVary

Syntax: ModPagespeedRespectVary on|off (Apache) · pagespeed RespectVary on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Whether to respect Vary headers for resources. Vary is always respected for HTML.

When enabled, resources whose Vary header indicates per-request variation are not rewritten.

RespectXForwardedProto

Syntax: ModPagespeedRespectXForwardedProto on|off (Apache) · pagespeed RespectXForwardedProto on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Whether to respect the X-Forwarded-Proto header.

ServeStaleIfFetchError

Syntax: pagespeed ServeStaleIfFetchError on|off; (nginx)
Default: on
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ServeStaleWhileRevalidateThresholdSec

Syntax: ModPagespeedServeStaleWhileRevalidateThresholdSec number (Apache) · pagespeed ServeStaleWhileRevalidateThresholdSec number; (nginx)
Default: 0
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Threshold for serving serving stale responses while revalidating in background. 0 means don’t serve stale content.Note: Stale response will be served only for non-html requests.

ServeXhrAccessControlHeaders

Syntax: ModPagespeedServeXhrAccessControlHeaders on|off (Apache) · pagespeed ServeXhrAccessControlHeaders on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Serve access control headers with response headers

StickyQueryParameters

Syntax: ModPagespeedStickyQueryParameters value (Apache) · pagespeed StickyQueryParameters value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The token that must be set by the PageSpeedStickyQueryParameters query parameter/header in a request to enable the setting of cookies for all other PageSpeed query parameters/headers in the request. Blank means it is disabled.

SupportNoScriptEnabled

Syntax: ModPagespeedSupportNoScriptEnabled on|off (Apache) · pagespeed SupportNoScriptEnabled on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Support for clients with no script support, in filters that insert new javascript.

TrackOriginalContentLength

Syntax: ModPagespeedTrackOriginalContentLength on|off (Apache) · pagespeed TrackOriginalContentLength on|off; (nginx)
Default: —
Context: Apache: server config · nginx: http

Add X-Original-Content-Length headers to rewritten resources

UrlSigningKey

Syntax: ModPagespeedUrlSigningKey value (Apache) · pagespeed UrlSigningKey value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Key used for signing .pagespeed resource URLs.

XHeaderValue

Syntax: ModPagespeedXHeaderValue value (Apache) · pagespeed XHeaderValue value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Set the value for the X-Mod-Pagespeed HTTP header

Sets the value of the X-Mod-Pagespeed (Apache) or X-Page-Speed (nginx, IIS) response header. The default is the module version string.

In-place resource optimization

CacheSmallImagesUnrewritten, InPlacePreemptiveRewriteCss, InPlacePreemptiveRewriteCssImages, InPlacePreemptiveRewriteImages, InPlacePreemptiveRewriteJavascript, InPlaceResourceOptimization, InPlaceRewriteDeadlineMs, InPlaceSMaxAgeSec, InPlaceWaitForOptimized, IproMaxConcurrentRecordings, IproMaxResponseBytes, NoTransformOptimizedImages, ProactivelyFreshenUserFacingRequest, ProactiveResourceFreshening

CacheSmallImagesUnrewritten

Syntax: pagespeed CacheSmallImagesUnrewritten on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

InPlacePreemptiveRewriteCss

Syntax: ModPagespeedInPlacePreemptiveRewriteCss on|off (Apache) · pagespeed InPlacePreemptiveRewriteCss on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If set, issue preemptive rewrites of CSS on the HTML path when configured to use IPRO.

InPlacePreemptiveRewriteCssImages

Syntax: ModPagespeedInPlacePreemptiveRewriteCssImages on|off (Apache) · pagespeed InPlacePreemptiveRewriteCssImages on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If set, issue preemptive rewrites of CSS images on the IPRO serving path.

InPlacePreemptiveRewriteImages

Syntax: ModPagespeedInPlacePreemptiveRewriteImages on|off (Apache) · pagespeed InPlacePreemptiveRewriteImages on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If set, issue preemptive rewrites of images on the HTML path when configured to use IPRO.

InPlacePreemptiveRewriteJavascript

Syntax: ModPagespeedInPlacePreemptiveRewriteJavascript on|off (Apache) · pagespeed InPlacePreemptiveRewriteJavascript on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If set, issue preemptive rewrites of JS on the HTML path when configured to use IPRO.

InPlaceResourceOptimization

Syntax: ModPagespeedInPlaceResourceOptimization on|off (Apache) · pagespeed InPlaceResourceOptimization on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow rewriting resources even when they are fetched over non-pagespeed URLs.

InPlaceRewriteDeadlineMs

Syntax: ModPagespeedInPlaceRewriteDeadlineMs number (Apache) · pagespeed InPlaceRewriteDeadlineMs number; (nginx)
Default: 10
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Time to wait for an in-place resource optimization beforefalling back to the original resource for the request.

InPlaceSMaxAgeSec

Syntax: ModPagespeedInPlaceSMaxAgeSec number (Apache) · pagespeed InPlaceSMaxAgeSec number; (nginx)
Default: 10
Context: Apache: server config, virtual host · nginx: http, server

What to set s-maxage to on not-yet-optimized ipro resources

InPlaceWaitForOptimized

Syntax: ModPagespeedInPlaceWaitForOptimized on|off (Apache) · pagespeed InPlaceWaitForOptimized on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Wait for optimizations to complete

IproMaxConcurrentRecordings

Syntax: ModPagespeedIproMaxConcurrentRecordings number (Apache) · pagespeed IproMaxConcurrentRecordings number; (nginx)
Default: 10
Context: Apache: server config, virtual host (tolerated) · nginx: http

Limit allowed number of IPRO recordings

IproMaxResponseBytes

Syntax: ModPagespeedIproMaxResponseBytes number (Apache) · pagespeed IproMaxResponseBytes number; (nginx)
Default: 10485760
Context: Apache: server config, virtual host (tolerated) · nginx: http

Limit allowed size of IPRO responses. Set to 0 for unlimited.

NoTransformOptimizedImages

Syntax: ModPagespeedNoTransformOptimizedImages on|off (Apache) · pagespeed NoTransformOptimizedImages on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Add no-transform header to cache-control for optimized images

ProactivelyFreshenUserFacingRequest

Syntax: pagespeed ProactivelyFreshenUserFacingRequest on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ProactiveResourceFreshening

Syntax: ModPagespeedProactiveResourceFreshening on|off (Apache) · pagespeed ProactiveResourceFreshening on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

If true, allows proactive freshening of inputs to the resource when they are close to expiry.

Domains and URLs

ClientDomainRewrite, CssPreserveURLs, Domain, DomainRewriteCookies, DomainRewriteHyperlinks, DomainShardCount, ImagePreserveURLs, JsPreserveURLs, LoadFromFile, LoadFromFileCacheTtlMs, LoadFromFileMatch, LoadFromFileRule, LoadFromFileRuleMatch, MapOriginDomain, MapProxyDomain, MapRewriteDomain, MaxSegmentLength, MaxUrlSize, PreserveUrlRelativity, ProxySuffix, RemoteConfigurationTimeoutMs, RemoteConfigurationUrl, ShardDomain, StaticAssetCDN, StaticAssetPrefix, UrlValuedAttribute

ClientDomainRewrite

Syntax: ModPagespeedClientDomainRewrite on|off (Apache) · pagespeed ClientDomainRewrite on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow rewrite_domains to rewrite urls on the client side.

CssPreserveURLs

Syntax: ModPagespeedCssPreserveURLs on|off (Apache) · pagespeed CssPreserveURLs on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Disable the rewriting of CSS URLs.

Domain

Syntax: ModPagespeedDomain domain (Apache) · pagespeed Domain domain; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Authorizes the module to fetch and rewrite resources on this domain.

DomainRewriteCookies

Syntax: ModPagespeedDomainRewriteCookies on|off (Apache) · pagespeed DomainRewriteCookies on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow rewrite_domains to rewrite domains in Set-Cookie headers.

DomainRewriteHyperlinks

Syntax: ModPagespeedDomainRewriteHyperlinks on|off (Apache) · pagespeed DomainRewriteHyperlinks on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow rewrite_domains to rewrite <form> and <a> tags in addition to resource tags.

DomainShardCount

Syntax: pagespeed DomainShardCount number; (nginx)
Default: 0
Context: nginx: http, server, location · also per request (query parameter)
Platform: nginx only

The module source carries no help text for this option.

ImagePreserveURLs

Syntax: ModPagespeedImagePreserveURLs on|off (Apache) · pagespeed ImagePreserveURLs on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Disable the rewriting of Image URLs.

JsPreserveURLs

Syntax: ModPagespeedJsPreserveURLs on|off (Apache) · pagespeed JsPreserveURLs on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Disable the rewriting of Javascript URLs.

LoadFromFile

Syntax: ModPagespeedLoadFromFile url_prefix filename_prefix (Apache) · pagespeed LoadFromFile url_prefix filename_prefix; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Serves resources under a URL prefix straight from the filesystem instead of fetching them over HTTP.

LoadFromFileCacheTtlMs

Syntax: ModPagespeedLoadFromFileCacheTtlMs number (Apache) · pagespeed LoadFromFileCacheTtlMs number; (nginx)
Default: 300000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Time in milliseconds to cache resources loaded from file that lack an Expires or Cache-Control header. If not explicitly set, defaults to using the value set by implicit_cache_ttl_ms

LoadFromFileMatch

Syntax: ModPagespeedLoadFromFileMatch url_regexp filename_prefix (Apache) · pagespeed LoadFromFileMatch url_regexp filename_prefix; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

LoadFromFile with a regular expression on the URL and a replacement filename prefix.

LoadFromFileRule

Syntax: ModPagespeedLoadFromFileRule Allow|Disallow filename_prefix (Apache) · pagespeed LoadFromFileRule Allow|Disallow filename_prefix; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Allows or disallows loading from file for a filename prefix after a LoadFromFile mapping.

LoadFromFileRuleMatch

Syntax: ModPagespeedLoadFromFileRuleMatch Allow|Disallow filename_regexp (Apache) · pagespeed LoadFromFileRuleMatch Allow|Disallow filename_regexp; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

LoadFromFileRule with a regular expression on the filename.

MapOriginDomain

Syntax: ModPagespeedMapOriginDomain to_domain from_domain[,from_domain...] [host_header] (Apache) · pagespeed MapOriginDomain to_domain from_domain[,from_domain...] [host_header]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Fetches resources for the public domain(s) from the origin domain instead, optionally sending a different Host header.

MapProxyDomain

Syntax: ModPagespeedMapProxyDomain proxy_domain origin_domain [to_domain] (Apache) · pagespeed MapProxyDomain proxy_domain origin_domain [to_domain]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Proxies and optimizes resources from a separate origin domain under a path of this site.

MapRewriteDomain

Syntax: ModPagespeedMapRewriteDomain to_domain from_domain[,from_domain...] (Apache) · pagespeed MapRewriteDomain to_domain from_domain[,from_domain...]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Rewrites optimized resource URLs from the listed domains onto another domain (for example a CDN hostname).

MaxSegmentLength

Syntax: ModPagespeedMaxSegmentLength number (Apache) · pagespeed MaxSegmentLength number; (nginx)
Default: 1024
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Maximum size of a URL segment.

Why and when to lower it is in URL segment length limits.

MaxUrlSize

Syntax: pagespeed MaxUrlSize number; (nginx)
Default: 2083
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

PreserveUrlRelativity

Syntax: ModPagespeedPreserveUrlRelativity on|off (Apache) · pagespeed PreserveUrlRelativity on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Keep rewritten URLs as relative as the original resource URL was.

When enabled, relative URLs in rewritten HTML stay relative instead of being converted to absolute URLs.

ProxySuffix

Syntax: ModPagespeedProxySuffix suffix (Apache) · pagespeed ProxySuffix suffix; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Sets up a proxy suffix to be used when slurping.

RemoteConfigurationTimeoutMs

Syntax: ModPagespeedRemoteConfigurationTimeoutMs number (Apache) · pagespeed RemoteConfigurationTimeoutMs number; (nginx)
Default: 1000
Context: Apache: server config, virtual host · nginx: http, server

Timeout for fetch of remote configuration file.

RemoteConfigurationUrl

Syntax: ModPagespeedRemoteConfigurationUrl value (Apache) · pagespeed RemoteConfigurationUrl value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

URL of site from which to pull remote configuration files

ShardDomain

Syntax: ModPagespeedShardDomain from_domain shard_domain[,shard_domain...] (Apache) · pagespeed ShardDomain from_domain shard_domain[,shard_domain...]; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Spreads optimized resource URLs for a domain across the listed shard domains.

StaticAssetCDN

Syntax: ModPagespeedStaticAssetCDN value (Apache) · pagespeed StaticAssetCDN value; (nginx)
Default: (empty)
Context: Apache: server config · nginx: http

Configures serving of helper scripts from external URLs rather than from compiled-in versions via static handler.

StaticAssetPrefix

Syntax: ModPagespeedStaticAssetPrefix url_prefix (Apache) · pagespeed StaticAssetPrefix url_prefix; (nginx)
Default: —
Context: Apache: server config · nginx: http

Where to serve static support files for pagespeed filters from.

URL prefix the module serves its own static assets from (the JavaScript libraries and images some filters inject). The default is /pagespeed_static/.

UrlValuedAttribute

Syntax: ModPagespeedUrlValuedAttribute element attribute category (Apache) · pagespeed UrlValuedAttribute element attribute category; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Declares an extra element attribute that holds a URL, with the resource category (image, script, stylesheet, otherResource, hyperlink) it should be treated as.

Optimizer worker

DaemonApiSocketPath, DaemonServeStoredEncodings, DaemonSocketPath, DaemonVolumePath

DaemonApiSocketPath

Syntax: ModPagespeedDaemonApiSocketPath value (Apache) · pagespeed DaemonApiSocketPath value; (nginx)
Default: /run/pagespeed-optimizer/api.sock
Context: Apache: server config, virtual host · nginx: http, server

Path of the optimizer worker’s management API unix socket, backing the /v1/daemon/* admin endpoints. Empty disables them. This is a different socket from DaemonSocketPath (the notification socket).

On nginx: Set the unix socket path of the optimizer worker’s management API, backing the /v1/daemon/* admin endpoints. Empty disables them.

DaemonServeStoredEncodings

Syntax: ModPagespeedDaemonServeStoredEncodings on|off (Apache) · pagespeed DaemonServeStoredEncodings on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Serve the optimizer worker’s stored gzip and brotli copies of stylesheets, scripts and SVG images to clients that accept them, labelled with Content-Encoding, instead of compressing the uncompressed copy on the way out. Default off.

DaemonSocketPath

Syntax: ModPagespeedDaemonSocketPath value (Apache) · pagespeed DaemonSocketPath value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Path of the optimizer worker’s notification socket. Set this together with DaemonVolumePath to hand in-place optimization to the worker; leave both unset to keep the classic in-place path.

On nginx: Path of the optimizer worker’s notification socket. Set this together with DaemonVolumePath; leave both unset to keep the classic in-place path. With both set, the nginx port records through the worker and serves the optimized copies from its shared cache.

Set together with DaemonVolumePath to hand in-place optimization to the optimizer worker installed beside the module. The worker’s own flags are on Worker and reverse-proxy configuration.

DaemonVolumePath

Syntax: ModPagespeedDaemonVolumePath value (Apache) · pagespeed DaemonVolumePath value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Path of the optimizer worker’s shared cache volume. Keep this on a DIFFERENT path from FileCachePath. Set this together with DaemonSocketPath; leave both unset to keep the classic in-place path.

On nginx: Path of the optimizer worker’s shared cache volume. Keep this on a DIFFERENT path from FileCachePath. Set this together with DaemonSocketPath; leave both unset to keep the classic in-place path. With both set, the nginx port records through the worker and serves the optimized copies from its shared cache.

Keep this on a different path from FileCachePath. The worker creates the volume under its --cache-dir; see Worker and reverse-proxy configuration.

Bot authentication and licensing

RslCapDirectoryHost, RslCapEnforcement, RslCapIssuer, RslCapKeyDirectoryAllowlist, RslCapKeyDirectoryFile, RslCapKeyDirectoryRefreshSec, RslCapKeyDirectoryUrl, RslCapRequestedLicense, RslCapRequestedScope, WebBotAuth, WebBotAuthBotDetection, WebBotAuthDirectoryHost, WebBotAuthKeyDirectoryAllowlist, WebBotAuthKeyDirectoryFile, WebBotAuthKeyDirectoryRefreshSec, WebBotAuthKeyDirectoryUrl, WebBotAuthPublicCounter, WebBotAuthTelemetry, WebBotAuthVerifiedBots

RslCapDirectoryHost

Syntax: pagespeed RslCapDirectoryHost value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Operator-mapped issuer directory host passed to the key provider (plane-split, never request-derived). Ignored by the v1 static-file provider; used by the follow-up network provider. Default empty.

RslCapEnforcement

Syntax: pagespeed RslCapEnforcement on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

Enable RSL-CAP capability-token enforcement: an Authorization: License token is validated and the verdict is mapped to an inline 401/402. Never settles/meters. Default off.

See RSL-CAP enforcement.

RslCapIssuer

Syntax: pagespeed RslCapIssuer value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Optional issuer pin: when set, an otherwise-authorized token whose iss != this value is rejected (401). Use when a directory host may serve multiple issuers. Default empty.

RslCapKeyDirectoryAllowlist

Syntax: pagespeed RslCapKeyDirectoryAllowlist value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

SSRF allowlist: comma-separated https origins the RSL-CAP warm-fetch may contact. Empty => warm-fetch disabled (fail-closed). Default empty.

RslCapKeyDirectoryFile

Syntax: pagespeed RslCapKeyDirectoryFile value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Path to a local JWKS file (the issuer’s published key directory, copied locally by the operator) used to resolve RSL-CAP signing keys. v1: synchronous, no network fetch. Default empty.

RslCapKeyDirectoryRefreshSec

Syntax: pagespeed RslCapKeyDirectoryRefreshSec value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

RSL-CAP warm-fetch refresh interval in seconds (clamped). Empty => default 3600. Default empty.

RslCapKeyDirectoryUrl

Syntax: pagespeed RslCapKeyDirectoryUrl value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

HTTPS URL of the issuer’s JWKS directory, fetched off-request by a background thread and cached; the request path reads cache-only. Requires RslCapKeyDirectoryAllowlist and RslCapDirectoryHost. Default empty (no network fetch).

RslCapRequestedLicense

Syntax: pagespeed RslCapRequestedLicense value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

License id this route requires; a token must grant it (and the requested scope) to be authorized, else 402. Default empty.

RslCapRequestedScope

Syntax: pagespeed RslCapRequestedScope value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Scope this route requires; a token must grant it (and the requested license) to be authorized, else 402. Default empty.

WebBotAuth

Syntax: pagespeed WebBotAuth on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

Enable observe-only Web-Bot-Auth (RFC 9421) request classification, surfaced as $x_verified_bot. Never blocks. Default off.

WebBotAuthBotDetection

Syntax: pagespeed WebBotAuthBotDetection on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

Let a verified Web-Bot-Auth signature classify the request as an automated client for PageSpeed’s own bot detection, so a signed agent is recognised even when it presents a browser user-agent. Suppresses the measurement beacons and lazyload for that request; never blocks it. Requires WebBotAuth. Default off (verdict stays observe-only).

Opt-in: a cryptographically verified Web Bot Auth signature (RFC 9421) classifies the request as automated for the module’s own bot detection, so a signed agent is recognized even when it presents a browser user agent. Requires WebBotAuth. See Web Bot Auth.

WebBotAuthDirectoryHost

Syntax: pagespeed WebBotAuthDirectoryHost value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

The signer directory’s host identity: the warm-fetch cache key, paired with WebBotAuthKeyDirectoryUrl. Ignored by the local-file static provider. Never request-derived. Default empty.

WebBotAuthKeyDirectoryAllowlist

Syntax: pagespeed WebBotAuthKeyDirectoryAllowlist value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

SSRF allowlist: comma-separated https origins (scheme://host[

]) the warm-fetch may contact. Empty => warm-fetch disabled (fail-closed). Default empty.

WebBotAuthKeyDirectoryFile

Syntax: pagespeed WebBotAuthKeyDirectoryFile value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Path to a local JWKS file (the signer’s published key directory, copied locally by the operator) used to verify signatures. A1 v1: no network fetch. Default empty.

WebBotAuthKeyDirectoryRefreshSec

Syntax: pagespeed WebBotAuthKeyDirectoryRefreshSec value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Warm-fetch refresh interval in seconds (clamped). Empty => default 3600. Default empty.

WebBotAuthKeyDirectoryUrl

Syntax: pagespeed WebBotAuthKeyDirectoryUrl value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

HTTPS URL of the signer’s JWKS directory, fetched off-request by a background thread and cached; the request path reads cache-only and never fetches. Requires WebBotAuthKeyDirectoryAllowlist and WebBotAuthDirectoryHost. Default empty (no network fetch).

WebBotAuthPublicCounter

Syntax: pagespeed WebBotAuthPublicCounter value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Opt-in verified-crawl counter mode (experimental): off (default) | private | public. Enabling a non-off mode publishes a discoverable marker at /.well-known/webbotauth-counter; the exact document is gated by the PAGESPEED_WEB_BOT_AUTH_COUNTER_TOKEN env bearer token. Default off (endpoint invisible).

WebBotAuthTelemetry

Syntax: pagespeed WebBotAuthTelemetry on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

Count verified/signed-agent requests in the opt-in web_bot_auth_verified_signed_requests statistic (and non-web-bot-auth signature material in web_bot_auth_other_signature_requests). Default off.

WebBotAuthVerifiedBots

Syntax: pagespeed WebBotAuthVerifiedBots value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Verified-bot registry: comma-separated keyid=name pairs.

Statistics, console and logging

AdminDomains, AdminPath, ConsoleDomains, ConsolePath, GlobalAdminDomains, GlobalAdminPath, GlobalStatisticsDomains, GlobalStatisticsPath, InstallCrashHandler, ListOutstandingUrlsOnError, LogBackgroundRewrite, LogDir, LogMobilizationSamples, LogRewriteTiming, LogUrlIndices, MaxRewriteInfoLogSize, MessageBufferSize, MessagesDomains, MessagesPath, ReportUnloadTime, SlowFileLatencyUs, Statistics, StatisticsDomains, StatisticsLogging, StatisticsLoggingChartsCSS, StatisticsLoggingChartsJS, StatisticsLoggingIntervalMs, StatisticsLoggingMaxFileSizeKb, StatisticsPath, StrictAdminAccess, UsePerVHostStatistics

AdminDomains

Syntax: ModPagespeedAdminDomains Allow|Disallow domain_wildcard (Apache) · pagespeed AdminDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the per-host admin pages: Allow or Disallow a domain wildcard. Default: Allow *.

AdminPath

Syntax: pagespeed AdminPath value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Set the admin path. Ex: /pagespeed_admin

ConsoleDomains

Syntax: ModPagespeedConsoleDomains Allow|Disallow domain_wildcard (Apache) · pagespeed ConsoleDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the console page: Allow or Disallow a domain wildcard. Default: Allow *.

ConsolePath

Syntax: pagespeed ConsolePath value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Set the console path. Ex: /pagespeed_console

GlobalAdminDomains

Syntax: ModPagespeedGlobalAdminDomains Allow|Disallow domain_wildcard (Apache) · pagespeed GlobalAdminDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the global admin pages: Allow or Disallow a domain wildcard. Default: Allow *.

GlobalAdminPath

Syntax: pagespeed GlobalAdminPath value; (nginx)
Default: (empty)
Context: nginx: http
Platform: nginx only

Set the global admin path. Ex: /pagespeed_global_admin

GlobalStatisticsDomains

Syntax: ModPagespeedGlobalStatisticsDomains Allow|Disallow domain_wildcard (Apache) · pagespeed GlobalStatisticsDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the global statistics page: Allow or Disallow a domain wildcard. Default: Allow *.

GlobalStatisticsPath

Syntax: pagespeed GlobalStatisticsPath value; (nginx)
Default: (empty)
Context: nginx: http
Platform: nginx only

Set the global statistics path. Ex: /ngx_pagespeed_global_statistics

InstallCrashHandler

Syntax: ModPagespeedInstallCrashHandler on|off (Apache) · pagespeed InstallCrashHandler on|off; (nginx)
Default: —
Context: Apache: server config · nginx: http

Try to dump backtrace on crashes. For developer use

ListOutstandingUrlsOnError

Syntax: ModPagespeedListOutstandingUrlsOnError on|off (Apache) · pagespeed ListOutstandingUrlsOnError on|off; (nginx)
Default: —
Context: Apache: server config · nginx: http

Adds an error message into the log for every URL fetch in flight when the HTTP stack encounters a system error, e.g. Connection Refused

Enable it only while debugging fetch problems; it is noisy in production.

LogBackgroundRewrite

Syntax: pagespeed LogBackgroundRewrite on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

The module source carries no help text for this option.

LogDir

Syntax: ModPagespeedLogDir value (Apache) · pagespeed LogDir value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Directory to store logs in.

LogMobilizationSamples

Syntax: ModPagespeedLogMobilizationSamples on|off (Apache) · pagespeed LogMobilizationSamples on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Verbose debugging of all sample data generated by mobilization_label_filter.

LogRewriteTiming

Syntax: ModPagespeedLogRewriteTiming on|off (Apache) · pagespeed LogRewriteTiming on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Whether or not to report timing information about HtmlParse.

LogUrlIndices

Syntax: ModPagespeedLogUrlIndices on|off (Apache) · pagespeed LogUrlIndices on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Whether or not to log URL indices for rewriter applications.

MaxRewriteInfoLogSize

Syntax: pagespeed MaxRewriteInfoLogSize number; (nginx)
Default: 150
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

MessageBufferSize

Syntax: ModPagespeedMessageBufferSize bytes (Apache) · pagespeed MessageBufferSize bytes; (nginx)
Default: —
Context: Apache: server config · nginx: http

Size in bytes of the in-memory message history shown on the messages page; 0 disables it.

MessagesDomains

Syntax: ModPagespeedMessagesDomains Allow|Disallow domain_wildcard (Apache) · pagespeed MessagesDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the message history page: Allow or Disallow a domain wildcard. Default: Allow *.

MessagesPath

Syntax: pagespeed MessagesPath value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Set the messages path. Ex: /ngx_pagespeed_message

ReportUnloadTime

Syntax: ModPagespeedReportUnloadTime on|off (Apache) · pagespeed ReportUnloadTime on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Deprecated, no effect: the beacon is now sent on page-hide, which covers pre-onload abandonment without breaking bfcache.

SlowFileLatencyUs

Syntax: ModPagespeedSlowFileLatencyUs number (Apache) · pagespeed SlowFileLatencyUs number; (nginx)
Default: 50000
Context: Apache: server config, virtual host · nginx: http, server

Maximum time in microseconds to allow for file operations before logging and bumping a stat

Statistics

Syntax: ModPagespeedStatistics on|off (Apache) · pagespeed Statistics on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Whether to collect cross-process statistics.

StatisticsDomains

Syntax: ModPagespeedStatisticsDomains Allow|Disallow domain_wildcard (Apache) · pagespeed StatisticsDomains Allow|Disallow domain_wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server, location

Access control for the per-host statistics page: Allow or Disallow a domain wildcard. Default: Allow *.

StatisticsLogging

Syntax: ModPagespeedStatisticsLogging on|off (Apache) · pagespeed StatisticsLogging on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Whether to log statistics if they’re being collected.

StatisticsLoggingChartsCSS

Syntax: ModPagespeedStatisticsLoggingChartsCSS value (Apache) · pagespeed StatisticsLoggingChartsCSS value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Where to find an offline copy of the Google Charts Tools API CSS.

StatisticsLoggingChartsJS

Syntax: ModPagespeedStatisticsLoggingChartsJS value (Apache) · pagespeed StatisticsLoggingChartsJS value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Where to find an offline copy of the Google Charts Tools API JS.

StatisticsLoggingIntervalMs

Syntax: ModPagespeedStatisticsLoggingIntervalMs number (Apache) · pagespeed StatisticsLoggingIntervalMs number; (nginx)
Default: 600000
Context: Apache: server config, virtual host · nginx: http, server

How often to log statistics, in milliseconds.

StatisticsLoggingMaxFileSizeKb

Syntax: ModPagespeedStatisticsLoggingMaxFileSizeKb number (Apache) · pagespeed StatisticsLoggingMaxFileSizeKb number; (nginx)
Default: 1024
Context: Apache: server config, virtual host · nginx: http, server

Max size for statistics logging file.

StatisticsPath

Syntax: pagespeed StatisticsPath value; (nginx)
Default: (empty)
Context: nginx: http, server
Platform: nginx only

Set the statistics path. Ex: /ngx_pagespeed_statistics

StrictAdminAccess

Syntax: ModPagespeedStrictAdminAccess on|off (Apache) · pagespeed StrictAdminAccess on|off; (nginx)
Default: off
Context: Apache: server config · nginx: http

OPT-IN, default off. When on, the admin, statistics, console and message handlers deny non-loopback clients unless an explicit *Domains allowlist is configured. The loopback decision uses the validated client connection IP, not the Host header. When off (default) access checks behave exactly as before.

UsePerVHostStatistics

Syntax: ModPagespeedUsePerVHostStatistics on|off (Apache) · pagespeed UsePerVHostStatistics on|off; (nginx)
Default: —
Context: Apache: server config · nginx: http

If true, keep track of statistics per VHost and not just globally

Images

AvifAnimatedRecompressionQuality

Syntax: ModPagespeedAvifAnimatedRecompressionQuality number (Apache) · pagespeed AvifAnimatedRecompressionQuality number; (nginx)
Default: 50
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten animated avif images [-1,100], 100 refers to best quality, -1 uses ImageRecompressionQuality.

AvifQualityForSaveData

Syntax: ModPagespeedAvifQualityForSaveData number (Apache) · pagespeed AvifQualityForSaveData number; (nginx)
Default: 45
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality for the images which will be optimized to lossy AVIF format in the Save-Data mode. Use a value in [0,100] to explicitly set the quality. Use -1 to ignore the Save-Data header.

AvifRecompressionQuality

Syntax: ModPagespeedAvifRecompressionQuality number (Apache) · pagespeed AvifRecompressionQuality number; (nginx)
Default: 60
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten avif images [-1,100], 100 refers to best quality, -1 uses ImageRecompressionQuality.

AvifRecompressionQualityForSmallScreens

Syntax: ModPagespeedAvifRecompressionQualityForSmallScreens number (Apache) · pagespeed AvifRecompressionQualityForSmallScreens number; (nginx)
Default: 50
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten avif images for small screens. [-1,100], 100 refers to best quality, -1 falls back to AvifRecompressionQuality.

AvifTimeoutMs

Syntax: ModPagespeedAvifTimeoutMs number (Apache) · pagespeed AvifTimeoutMs number; (nginx)
Default: 5000
Context: Apache: server config, virtual host (tolerated) · nginx: http

Timeout for AVIF still-image encoding, in milliseconds; the encoder speed is derived from this budget.

CriticalImagesBeaconEnabled

Syntax: ModPagespeedCriticalImagesBeaconEnabled on|off (Apache) · pagespeed CriticalImagesBeaconEnabled on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Enable insertion of client-side critical image detection js for image optimization filters.

CssImageInlineMaxBytes

Syntax: ModPagespeedCssImageInlineMaxBytes number (Apache) · pagespeed CssImageInlineMaxBytes number; (nginx)
Default: 0
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which CSS images will be inlined.

EnableLazyLoadHighResImages

Syntax: pagespeed EnableLazyLoadHighResImages on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ImageInlineMaxBytes

Syntax: ModPagespeedImageInlineMaxBytes number (Apache) · pagespeed ImageInlineMaxBytes number; (nginx)
Default: 3072
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which images will be inlined.

ImageJpegNumProgressiveScans

Syntax: ModPagespeedImageJpegNumProgressiveScans number (Apache) · pagespeed ImageJpegNumProgressiveScans number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of progressive scans [1,10] to emit when rewriting images as ten-scan progressive jpegs. A value of -1 outputs all progressive scans.

ImageJpegNumProgressiveScansForSmallScreens

Syntax: ModPagespeedImageJpegNumProgressiveScansForSmallScreens number (Apache) · pagespeed ImageJpegNumProgressiveScansForSmallScreens number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of progressive scans [1,10] to emit when rewriting images asten-scan progressive jpegs for small screens. A value of -1 falls back to kImageJpegNumProgressiveScans.

ImageLimitOptimizedPercent

Syntax: ModPagespeedImageLimitOptimizedPercent number (Apache) · pagespeed ImageLimitOptimizedPercent number; (nginx)
Default: 100
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Replace images whose size after recompression is less than the given percent of original image size; 100 means replace if smaller.

ImageLimitRenderedAreaPercent

Syntax: ModPagespeedImageLimitRenderedAreaPercent number (Apache) · pagespeed ImageLimitRenderedAreaPercent number; (nginx)
Default: 95
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Limit on percentage of rendered image wxh to the original image wxh that should be stored in the property cache. This is to avoid corner cases where rounding off decreases the rendered image size by a few pixels.

ImageLimitResizeAreaPercent

Syntax: ModPagespeedImageLimitResizeAreaPercent number (Apache) · pagespeed ImageLimitResizeAreaPercent number; (nginx)
Default: 100
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Consider resizing images whose area in pixels is less than the given percent of original image area; 100 means replace if smaller.

ImageMaxRewritesAtOnce

Syntax: ModPagespeedImageMaxRewritesAtOnce number (Apache) · pagespeed ImageMaxRewritesAtOnce number; (nginx)
Default: 8
Context: Apache: server config, virtual host (tolerated) · nginx: http

Set bound on number of images being rewritten at one time (0 = unbounded).

ImageProvenanceCarry

Syntax: ModPagespeedImageProvenanceCarry on|off (Apache) · pagespeed ImageProvenanceCarry on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Provenance carry-through: when true (and PreserveImageProvenance is on), PNG images carrying a C2PA / Content Credentials manifest are recompressed AND their original manifest chunks (caBX/iTXt) are carried into the optimized output unmodified, keeping both the byte savings and the provenance. (Manifest-bearing JPEGs already carry their APP11/JUMBF through recompression under PreserveImageProvenance.) Cases where the carrier cannot be preserved byte-exactly — resize, format conversion (PNG->JPEG/WebP), GIF, or extraction failure — fall back to the default detect-and-skip pass-through. No effect when PreserveImageProvenance is false.

ImageRecompressionQuality

Syntax: ModPagespeedImageRecompressionQuality number (Apache) · pagespeed ImageRecompressionQuality number; (nginx)
Default: 85
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality parameter for recompressing images [-1,100], 100 refers to best quality, -1 disables lossy compression. JpegRecompressionQuality and WebpRecompressionQuality override this.

ImageResolutionLimitBytes

Syntax: ModPagespeedImageResolutionLimitBytes number (Apache) · pagespeed ImageResolutionLimitBytes number; (nginx)
Default: 33554432
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Maximum byte size of an image for optimization

InlineOnlyCriticalImages

Syntax: ModPagespeedInlineOnlyCriticalImages on|off (Apache) · pagespeed InlineOnlyCriticalImages on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Inline only critical images

JpegQualityForSaveData

Syntax: ModPagespeedJpegQualityForSaveData number (Apache) · pagespeed JpegQualityForSaveData number; (nginx)
Default: 50
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality for the images which will be optimized to JPEG format in the Save-Data mode. Use a value in [0,100] to explicitly set the quality. Use -1 to ignore the Save-Data header.

JpegRecompressionQuality

Syntax: ModPagespeedJpegRecompressionQuality number (Apache) · pagespeed JpegRecompressionQuality number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality parameter for recompressing jpeg images [-1,100], 100 is lossless, -1 uses ImageRecompressionQuality

JpegRecompressionQualityForSmallScreens

Syntax: ModPagespeedJpegRecompressionQualityForSmallScreens number (Apache) · pagespeed JpegRecompressionQualityForSmallScreens number; (nginx)
Default: 70
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality parameter for recompressing jpeg images for small screens. [-1,100], 100 refers to best quality, -1 falls back to ImageJpegRecompressionQuality.

LazyloadImagesAfterOnload

Syntax: ModPagespeedLazyloadImagesAfterOnload on|off (Apache) · pagespeed LazyloadImagesAfterOnload on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Wait until page onload before loading lazy images

LazyloadImagesBlankUrl

Syntax: ModPagespeedLazyloadImagesBlankUrl value (Apache) · pagespeed LazyloadImagesBlankUrl value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

URL of image used to display prior to loading the lazy image. Empty means use a site-local copy.

LazyloadImagesMode

Syntax: ModPagespeedLazyloadImagesMode auto|native|js (Apache) · pagespeed LazyloadImagesMode auto|native|js; (nginx)
Default: auto
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

How to lazyload images: ‘native’ annotates non-critical images with loading=“lazy”, ‘js’ uses the JavaScript loader, and ‘auto’ (the default) picks per user agent.

LazyloadImagesSkipFirst

Syntax: ModPagespeedLazyloadImagesSkipFirst number (Apache) · pagespeed LazyloadImagesSkipFirst number; (nginx)
Default: 1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of leading images to leave untouched when critical image data is unavailable, protecting likely LCP candidates.

MaxImageSizeLowResolutionBytes

Syntax: ModPagespeedMaxImageSizeLowResolutionBytes number (Apache) · pagespeed MaxImageSizeLowResolutionBytes number; (nginx)
Default: 1048576
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Maximum image size below which low resolution image is generated.

MaxInlinedPreviewImagesIndex

Syntax: ModPagespeedMaxInlinedPreviewImagesIndex number (Apache) · pagespeed MaxInlinedPreviewImagesIndex number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of first N images for which low resolution image is generated. Negative values result in generation for all images.

MaxLowResImageSizeBytes

Syntax: pagespeed MaxLowResImageSizeBytes number; (nginx)
Default: -1
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

MaxLowResToHighResImageSizePercentage

Syntax: pagespeed MaxLowResToHighResImageSizePercentage number; (nginx)
Default: 100
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

MinImageSizeLowResolutionBytes

Syntax: ModPagespeedMinImageSizeLowResolutionBytes number (Apache) · pagespeed MinImageSizeLowResolutionBytes number; (nginx)
Default: 3072
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Minimum image size above which low resolution image is generated.

PreserveImageProvenance

Syntax: ModPagespeedPreserveImageProvenance on|off (Apache) · pagespeed PreserveImageProvenance on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Preserve C2PA/Content-Credentials provenance metadata (JPEG APP11/JUMBF) through image optimization. On by default; independent of EXIF stripping.

ProgressiveJpegMinBytes

Syntax: ModPagespeedProgressiveJpegMinBytes number (Apache) · pagespeed ProgressiveJpegMinBytes number; (nginx)
Default: 10240
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Minimum size in bytes for converting a jpeg to progressive

ResponsiveImageDensities

Syntax: ModPagespeedResponsiveImageDensities value (Apache) · pagespeed ResponsiveImageDensities value; (nginx)
Default: 1.5,2,3
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Comma separated list of screen densities to target with ResponsiveImageFilter srcsets.

ServeRewrittenAvifUrlsToAnyAgent

Syntax: ModPagespeedServeRewrittenAvifUrlsToAnyAgent on|off (Apache) · pagespeed ServeRewrittenAvifUrlsToAnyAgent on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Serve rewritten .avif images to any user-agent

ServeRewrittenWebpUrlsToAnyAgent

Syntax: ModPagespeedServeRewrittenWebpUrlsToAnyAgent on|off (Apache) · pagespeed ServeRewrittenWebpUrlsToAnyAgent on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Serve rewritten .webp images to any user-agent

UseBlankImageForInlinePreview

Syntax: ModPagespeedUseBlankImageForInlinePreview on|off (Apache) · pagespeed UseBlankImageForInlinePreview on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Use a blank image for inline preview

WebpAnimatedRecompressionQuality

Syntax: ModPagespeedWebpAnimatedRecompressionQuality number (Apache) · pagespeed WebpAnimatedRecompressionQuality number; (nginx)
Default: 70
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten animated webp images [-1,100], 100 refers to best quality, -1 uses ImageRecompressionQuality.

WebpQualityForSaveData

Syntax: ModPagespeedWebpQualityForSaveData number (Apache) · pagespeed WebpQualityForSaveData number; (nginx)
Default: 50
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Set quality for the images which will be optimized to lossy WebP format in the Save-Data mode. Use a value in [0,100] to explicitly set the quality. Use -1 to ignore the Save-Data header.

WebpRecompressionQuality

Syntax: ModPagespeedWebpRecompressionQuality number (Apache) · pagespeed WebpRecompressionQuality number; (nginx)
Default: 80
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten webp images [-1,100], 100 refers to best quality, -1 uses ImageRecompressionQuality.

WebpRecompressionQualityForSmallScreens

Syntax: ModPagespeedWebpRecompressionQualityForSmallScreens number (Apache) · pagespeed WebpRecompressionQualityForSmallScreens number; (nginx)
Default: 70
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Quality for rewritten webp images for small screens. [-1,100], 100 refers to best quality, -1 falls back to WebpRecompressionQuality.

WebpTimeoutMs

Syntax: pagespeed WebpTimeoutMs number; (nginx)
Default: -1
Context: nginx: http
Platform: nginx only

The module source carries no help text for this option.

CSS

AlwaysRewriteCss, CriticalCssAboveTheFoldOnly, CssFlattenMaxBytes, CssInlineMaxBytes, CssOutlineMinBytes, GoogleFontCssInlineMaxBytes, MaxCombinedCssBytes, PermitIdsForCssCombining, TestOnlyPrioritizeCriticalCssDontApplyOriginalCss

AlwaysRewriteCss

Syntax: pagespeed AlwaysRewriteCss on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

CriticalCssAboveTheFoldOnly

Syntax: ModPagespeedCriticalCssAboveTheFoldOnly on|off (Apache) · pagespeed CriticalCssAboveTheFoldOnly on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Makes prioritize_critical_css inline only the rules for content in the first screen instead of the rules for the whole page. The inline block is smaller; content further down may be shown partly styled until the full stylesheet has arrived.

CssFlattenMaxBytes

Syntax: ModPagespeedCssFlattenMaxBytes number (Apache) · pagespeed CssFlattenMaxBytes number; (nginx)
Default: 1024000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which stylesheets will be flattened.

CssInlineMaxBytes

Syntax: ModPagespeedCssInlineMaxBytes number (Apache) · pagespeed CssInlineMaxBytes number; (nginx)
Default: 2048
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which stylesheets will be inlined.

CssOutlineMinBytes

Syntax: ModPagespeedCssOutlineMinBytes number (Apache) · pagespeed CssOutlineMinBytes number; (nginx)
Default: 3000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of bytes above which inline CSS resources will be outlined.

GoogleFontCssInlineMaxBytes

Syntax: ModPagespeedGoogleFontCssInlineMaxBytes number (Apache) · pagespeed GoogleFontCssInlineMaxBytes number; (nginx)
Default: 49152
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which Google Font stylesheets will be inlined.

MaxCombinedCssBytes

Syntax: ModPagespeedMaxCombinedCssBytes number (Apache) · pagespeed MaxCombinedCssBytes number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Maximum size allowed for the combined CSS resource.

PermitIdsForCssCombining

Syntax: ModPagespeedPermitIdsForCssCombining wildcard (Apache) · pagespeed PermitIdsForCssCombining wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Allow combining CSS files with IDs matching wildcard

TestOnlyPrioritizeCriticalCssDontApplyOriginalCss

Syntax: ModPagespeedTestOnlyPrioritizeCriticalCssDontApplyOriginalCss on|off (Apache) · pagespeed TestOnlyPrioritizeCriticalCssDontApplyOriginalCss on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Stops the prioritize_critical_css filter from invoking its JavaScript that applies all the ‘hidden’ CSS at onload. Intended for testing.

JavaScript

AvoidRenamingIntrospectiveJavascript, ClearInheritedScripts, EnableDeferJsExperimental, EnablePrioritizingScripts, JsInlineMaxBytes, JsOutlineMinBytes, Library, MaxCombinedJsBytes, ProcessScriptVariables, UseAnalyticsJs

AvoidRenamingIntrospectiveJavascript

Syntax: ModPagespeedAvoidRenamingIntrospectiveJavascript on|off (Apache) · pagespeed AvoidRenamingIntrospectiveJavascript on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Don’t combine, inline, cache extend, or otherwise modify javascript in ways that require changing the URL if we see introspection in the form of document.getElementsByTagName(‘script’).

ClearInheritedScripts

Syntax: pagespeed ClearInheritedScripts; (nginx)
Default: —
Context: nginx: http, server, location
Platform: nginx only

Drops the script-variable directive lines inherited from the enclosing block, so this block starts from the non-scripted configuration.

EnableDeferJsExperimental

Syntax: ModPagespeedEnableDeferJsExperimental on|off (Apache) · pagespeed EnableDeferJsExperimental on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Enable experimental options in defer javascript.

EnablePrioritizingScripts

Syntax: pagespeed EnablePrioritizingScripts on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

JsInlineMaxBytes

Syntax: ModPagespeedJsInlineMaxBytes number (Apache) · pagespeed JsInlineMaxBytes number; (nginx)
Default: 2048
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Number of bytes below which javascript will be inlined.

JsOutlineMinBytes

Syntax: ModPagespeedJsOutlineMinBytes number (Apache) · pagespeed JsOutlineMinBytes number; (nginx)
Default: 3000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of bytes above which inline Javascript resources willbe outlined.

Library

Syntax: ModPagespeedLibrary bytes md5 canonical_url (Apache) · pagespeed Library bytes md5 canonical_url; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Recognizes a JavaScript library by size and hash so canonicalize_javascript_libraries can replace it with the given canonical URL.

MaxCombinedJsBytes

Syntax: ModPagespeedMaxCombinedJsBytes number (Apache) · pagespeed MaxCombinedJsBytes number; (nginx)
Default: 92160
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Maximum size allowed for the combined JavaScript resource.

ProcessScriptVariables

Syntax: pagespeed ProcessScriptVariables on|off|all; (nginx)
Default: —
Context: nginx: http
Platform: nginx only

Evaluate nginx script variables ($var) in pagespeed directive arguments at request time: off, on (the LoadFromFile*, EnableFilters, DisableFilters, DownstreamCache* and ShardDomain directives) or all (every query- and directory-scoped option too). Settable once, at the top level.

UseAnalyticsJs

Syntax: ModPagespeedUseAnalyticsJs on|off (Apache) · pagespeed UseAnalyticsJs on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Log to analytics.js instead of ga.js with insert_ga.

Caching

AsyncMetadataL2Writes, AwaitPcacheLookup, CacheFlushFilename, CacheFlushPollIntervalSec, CacheFragment, CompressMetadataCache, CreateSharedMemoryMetadataCache, CycloneRamCacheKb, CycloneZeroCopy, CycloneZeroCopyServe, DefaultCacheHtml, DefaultSharedMemoryCacheKB, DownstreamCachePurgeLocationPrefix, DownstreamCachePurgeMethod, DownstreamCacheRebeaconingKey, DownstreamCacheRewrittenPercentageThreshold, EnableCachePurge, FileCachePath, FileCacheSizeKb, FileCacheSmallTierPercent, FinderPropertiesCacheExpirationTimeMs, FinderPropertiesCacheRefreshTimeMs, ForceCaching, HttpCacheCompressionLevel, ImplicitCacheTtlMs, LRUCacheByteLimit, LRUCacheKbPerProcess, MaxCacheableContentLength, MaxHtmlCacheTimeMs, MemcachedServers, MemcachedThreads, MemcachedTimeoutUs, MetadataCacheStalenessThresholdMs, MinResourceCacheTimeToRewriteMs, NonCacheablesForCachePartialHtml, OverrideCachingTtlMs, PubliclyCacheMismatchedHashesExperimental, PurgeMethod, RedisDatabaseIndex, RedisReconnectionDelayMs, RedisServer, RedisTimeoutUs, RedisTTLSec, SharedMemoryLocks, ShmMetadataCacheCheckpointIntervalSec, UseFallbackPropertyCacheValues

AsyncMetadataL2Writes

Syntax: ModPagespeedAsyncMetadataL2Writes on|off (Apache) · pagespeed AsyncMetadataL2Writes on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Defer the metadata cache’s blocking L2 (disk) write off the rewrite critical path onto a single-thread write-behind queue. Reads and the shared-memory L1 write stay synchronous, so same-machine read-your-writes is preserved. Experimental; off by default.

AwaitPcacheLookup

Syntax: pagespeed AwaitPcacheLookup on|off; (nginx)
Default: off
Context: nginx: http, server
Platform: nginx only

The module source carries no help text for this option.

CacheFlushFilename

Syntax: ModPagespeedCacheFlushFilename value (Apache) · pagespeed CacheFlushFilename value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Name of file to check for timestamp updates used to flush cache. This file will be relative to the ModPagespeedFileCachePath if it does not begin with a slash.

CacheFlushPollIntervalSec

Syntax: ModPagespeedCacheFlushPollIntervalSec number (Apache) · pagespeed CacheFlushPollIntervalSec number; (nginx)
Default: 5
Context: Apache: server config, virtual host · nginx: http, server

Number of seconds to wait between polling for cache-flush requests

CacheFragment

Syntax: ModPagespeedCacheFragment value (Apache) · pagespeed CacheFragment value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Set a cache fragment to allow servers with different hostnames to share a cache. Allowed: letters, numbers, underscores, and hyphens.

CompressMetadataCache

Syntax: ModPagespeedCompressMetadataCache on|off (Apache) · pagespeed CompressMetadataCache on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Whether to compress cache entries before writing them to memory or disk.

CreateSharedMemoryMetadataCache

Syntax: ModPagespeedCreateSharedMemoryMetadataCache name size_kb (Apache) · pagespeed CreateSharedMemoryMetadataCache name size_kb; (nginx)
Default: —
Context: Apache: server config · nginx: http

Creates a named shared-memory metadata cache of the given size for the virtual hosts whose FileCachePath is that name.

CycloneRamCacheKb

Syntax: ModPagespeedCycloneRamCacheKb number (Apache) · pagespeed CycloneRamCacheKb number; (nginx)
Default: 0
Context: Apache: server config, virtual host · nginx: http, server

Set the size, in KB, of Cyclone’s internal RAM cache tier, decoupled from LRUCacheKbPerProcess. 0 (the default) disables the RAM tier — reads are served from the memory-mapped volume, which the OS page cache already keeps hot; -1 inherits LRUCacheKbPerProcess.

CycloneZeroCopy

Syntax: ModPagespeedCycloneZeroCopy on|off (Apache) · pagespeed CycloneZeroCopy on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Serve HTTP cache hits directly from the Cyclone cache’s memory-mapped storage without copying the payload (zero-copy). Off by default on every port; set it on explicitly to opt in.

CycloneZeroCopyServe

Syntax: ModPagespeedCycloneZeroCopyServe on|off (Apache) · pagespeed CycloneZeroCopyServe on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Carry memory-mapped Cyclone cache-hit bytes into the port output buffer by reference (aliased) instead of copying them; the serve safely copies the tail out before a cache eviction can overwrite it. Engages only once CycloneZeroCopy maps cache values; on Apache the aliased serve is experimental and activates only when this option is explicitly set. Apache aliases only plain-HTTP/1.x main-request 200s of at least 16KB served verbatim (no Range, no deflate/ssl/http2 or other transforming filter), and bytes an output filter parks for a slow client are copied out at that point; everything else serves a verified copy.

DefaultCacheHtml

Syntax: pagespeed DefaultCacheHtml on|off; (nginx)
Default: off
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

DefaultSharedMemoryCacheKB

Syntax: ModPagespeedDefaultSharedMemoryCacheKB number (Apache) · pagespeed DefaultSharedMemoryCacheKB number; (nginx)
Default: 51200
Context: Apache: server config, virtual host (tolerated) · nginx: http

Size of the default shared memory cache used by all virtual hosts that don’t use CreateSharedMemoryMetadataCache. Set to 0 to turn off the default shared memory cache.

DownstreamCachePurgeLocationPrefix

Syntax: ModPagespeedDownstreamCachePurgeLocationPrefix host:port/path (Apache) · pagespeed DownstreamCachePurgeLocationPrefix host:port/path; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The host

/path prefix to be used for purging requests from the downstream cache.

DownstreamCachePurgeMethod

Syntax: ModPagespeedDownstreamCachePurgeMethod value (Apache) · pagespeed DownstreamCachePurgeMethod value; (nginx)
Default: PURGE
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Method to be used for purging responses from the downstream cache

DownstreamCacheRebeaconingKey

Syntax: ModPagespeedDownstreamCacheRebeaconingKey value (Apache) · pagespeed DownstreamCacheRebeaconingKey value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

The key used to authenticate rebeaconing requests from downstream caches. The value specified for this key in the pagespeed server config should be used in the caching layer configuration also.

DownstreamCacheRewrittenPercentageThreshold

Syntax: ModPagespeedDownstreamCacheRewrittenPercentageThreshold number (Apache) · pagespeed DownstreamCacheRewrittenPercentageThreshold number; (nginx)
Default: 95
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Threshold for percentage of rewriting to be finished before the response is served out and simultaneously stored in the downstream cache, beyond which the response will not be purged from the cache evenif more rewriting is possible now

EnableCachePurge

Syntax: ModPagespeedEnableCachePurge on|off (Apache) · pagespeed EnableCachePurge on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Allows individual resources to be flushed; adding some overhead to the metadata cache

FileCachePath

Syntax: ModPagespeedFileCachePath value (Apache) · pagespeed FileCachePath value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Set the path for file cache

FileCacheSizeKb

Syntax: ModPagespeedFileCacheSizeKb number (Apache) · pagespeed FileCacheSizeKb number; (nginx)
Default: 1048576
Context: Apache: server config, virtual host · nginx: http, server

Set the target size (in kilobytes) for file cache

FileCacheSmallTierPercent

Syntax: ModPagespeedFileCacheSmallTierPercent number (Apache) · pagespeed FileCacheSmallTierPercent number; (nginx)
Default: 10
Context: Apache: server config, virtual host · nginx: http, server

Percentage of the file cache carved out as a separate small-object volume that protects metadata and property entries from payload churn. 0 disables the tier; values are clamped to [0, 50]. Below roughly 256 MB of total file cache the tier disables itself and entries share the main volume. Applies in the default shared-memory metadata cache configuration; with the shm metadata cache disabled, metadata stays on the main volume.

FinderPropertiesCacheExpirationTimeMs

Syntax: ModPagespeedFinderPropertiesCacheExpirationTimeMs number (Apache) · pagespeed FinderPropertiesCacheExpirationTimeMs number; (nginx)
Default: 7200000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Number of ms that beacon results for the critical selector finders should be considered valid.

FinderPropertiesCacheRefreshTimeMs

Syntax: pagespeed FinderPropertiesCacheRefreshTimeMs number; (nginx)
Default: 5400000
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ForceCaching

Syntax: ModPagespeedForceCaching on|off (Apache) · pagespeed ForceCaching on|off; (nginx)
Default: —
Context: Apache: server config · nginx: http

Ignore HTTP cache headers and TTLs

HttpCacheCompressionLevel

Syntax: ModPagespeedHttpCacheCompressionLevel number (Apache) · pagespeed HttpCacheCompressionLevel number; (nginx)
Default: 9
Context: Apache: server config, virtual host · nginx: http, server

Compression level for HTTPCache. [-1-9] where 0 is off, 1 is minimumcompression, and 9 (the default) is maximum compression.

ImplicitCacheTtlMs

Syntax: ModPagespeedImplicitCacheTtlMs number (Apache) · pagespeed ImplicitCacheTtlMs number; (nginx)
Default: 300000
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Time in milliseconds to cache resources that lack an Expires or Cache-Control header

LRUCacheByteLimit

Syntax: ModPagespeedLRUCacheByteLimit number (Apache) · pagespeed LRUCacheByteLimit number; (nginx)
Default: 0
Context: Apache: server config, virtual host · nginx: http, server

Set the maximum byte size entry to store in the per-process in-memory LRU cache

LRUCacheKbPerProcess

Syntax: ModPagespeedLRUCacheKbPerProcess number (Apache) · pagespeed LRUCacheKbPerProcess number; (nginx)
Default: 0
Context: Apache: server config, virtual host · nginx: http, server

Set the total size, in KB, of the per-process in-memory LRU cache

MaxCacheableContentLength

Syntax: ModPagespeedMaxCacheableContentLength number (Apache) · pagespeed MaxCacheableContentLength number; (nginx)
Default: 16777216
Context: Apache: server config, virtual host · nginx: http, server

Maximum length of a cacheable response content. To remove this limit, use -1.

MaxHtmlCacheTimeMs

Syntax: pagespeed MaxHtmlCacheTimeMs number; (nginx)
Default: 0
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

MemcachedServers

Syntax: ModPagespeedMemcachedServers value (Apache) · pagespeed MemcachedServers value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Comma-separated list of servers e.g. host1

,host2

MemcachedThreads

Syntax: ModPagespeedMemcachedThreads number (Apache) · pagespeed MemcachedThreads number; (nginx)
Default: 1
Context: Apache: server config, virtual host · nginx: http, server

Number of background threads to use to run memcached fetches

MemcachedTimeoutUs

Syntax: ModPagespeedMemcachedTimeoutUs number (Apache) · pagespeed MemcachedTimeoutUs number; (nginx)
Default: 500000
Context: Apache: server config, virtual host · nginx: http, server

Maximum time in microseconds to allow for memcached transactions

MetadataCacheStalenessThresholdMs

Syntax: pagespeed MetadataCacheStalenessThresholdMs number; (nginx)
Default: 0
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

MinResourceCacheTimeToRewriteMs

Syntax: pagespeed MinResourceCacheTimeToRewriteMs number; (nginx)
Default: 0
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

NonCacheablesForCachePartialHtml

Syntax: pagespeed NonCacheablesForCachePartialHtml value; (nginx)
Default: (empty)
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

OverrideCachingTtlMs

Syntax: pagespeed OverrideCachingTtlMs number; (nginx)
Default: -1
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

PubliclyCacheMismatchedHashesExperimental

Syntax: ModPagespeedPubliclyCacheMismatchedHashesExperimental on|off (Apache) · pagespeed PubliclyCacheMismatchedHashesExperimental on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

When serving a request for a .pagespeed. URL with the wrong hash, allow public caching based on the origin TTL.

PurgeMethod

Syntax: ModPagespeedPurgeMethod value (Apache) · pagespeed PurgeMethod value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

HTTP method used for Cache Purge requests. Typically this is set to PURGE, but you must ensure that only authorized clients have access to this method.

RedisDatabaseIndex

Syntax: ModPagespeedRedisDatabaseIndex number (Apache) · pagespeed RedisDatabaseIndex number; (nginx)
Default: 0
Context: Apache: server config, virtual host · nginx: http, server

Redis server database index selection

RedisReconnectionDelayMs

Syntax: ModPagespeedRedisReconnectionDelayMs number (Apache) · pagespeed RedisReconnectionDelayMs number; (nginx)
Default: 1000
Context: Apache: server config, virtual host · nginx: http, server

Time to wait after unsuccessful reconnection before another attempt (ms)

RedisServer

Syntax: ModPagespeedRedisServer value (Apache) · pagespeed RedisServer value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Redis server to use in format: <host>[:<port>]

RedisTimeoutUs

Syntax: ModPagespeedRedisTimeoutUs number (Apache) · pagespeed RedisTimeoutUs number; (nginx)
Default: 50000
Context: Apache: server config, virtual host · nginx: http, server

Timeout for all Redis operations and connection (us)

RedisTTLSec

Syntax: ModPagespeedRedisTTLSec number (Apache) · pagespeed RedisTTLSec number; (nginx)
Default: -1
Context: Apache: server config, virtual host · nginx: http, server

Redis key TTL to use (seconds)

SharedMemoryLocks

Syntax: ModPagespeedSharedMemoryLocks on|off (Apache) · pagespeed SharedMemoryLocks on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Use shared memory for internal named lock service

ShmMetadataCacheCheckpointIntervalSec

Syntax: ModPagespeedShmMetadataCacheCheckpointIntervalSec number (Apache) · pagespeed ShmMetadataCacheCheckpointIntervalSec number; (nginx)
Default: 300
Context: Apache: server config · nginx: http

How often to checkpoint the shared memory metadata cache to disk. Set to 0 to turn off checkpointing.

UseFallbackPropertyCacheValues

Syntax: ModPagespeedUseFallbackPropertyCacheValues on|off (Apache) · pagespeed UseFallbackPropertyCacheValues on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

If this is set to true, fallback values will be used from property cache if actual value is not present. Here fallback values means properties which are shared across all requests which have same url if query paramaters are removed. Example: http://www.test.com?a=1 and http://www.test.com?a=2 share same fallback properties though they are two different urls.

Fetching and origins

BlockingRewriteKey, BlockingRewriteRefererUrls, CustomFetchHeader, DangerPermitFetchFromUnknownHosts, ExperimentalMeasurementProxy, FetcherTimeOutMs, FetchHttps, FetchProxy, FetchWithGzip, NativeFetcherMaxKeepaliveRequests, RateLimitBackgroundFetches, SlurpDirectory, SlurpFlushLimit, SlurpReadOnly, SslCertDirectory, SslCertFile, TestProxy, TestProxySlurp, UseNativeFetcher

BlockingRewriteKey

Syntax: ModPagespeedBlockingRewriteKey value (Apache) · pagespeed BlockingRewriteKey value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

If the X-PSA-Pagespeed-Blocking-Rewrite header is present, and its value matches the configured value, ensure that all rewrites are completed before sending the response to the client.

BlockingRewriteRefererUrls

Syntax: ModPagespeedBlockingRewriteRefererUrls wildcard (Apache) · pagespeed BlockingRewriteRefererUrls wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

wildcard_spec for referer urls which trigger blocking rewrites

CustomFetchHeader

Syntax: ModPagespeedCustomFetchHeader name value (Apache) · pagespeed CustomFetchHeader name value; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Adds a request header to every fetch the module makes to an origin.

DangerPermitFetchFromUnknownHosts

Syntax: ModPagespeedDangerPermitFetchFromUnknownHosts on|off (Apache) · pagespeed DangerPermitFetchFromUnknownHosts on|off; (nginx)
Default: off
Context: Apache: server config · nginx: http

Disable security checks that prohibit fetching from hostnames mod_pagespeed does not know about

ExperimentalMeasurementProxy

Syntax: ModPagespeedExperimentalMeasurementProxy https://root.domain password (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Experimental measurement proxy mode (Apache only).

FetcherTimeOutMs

Syntax: ModPagespeedFetcherTimeOutMs number (Apache) · pagespeed FetcherTimeOutMs number; (nginx)
Default: 5000
Context: Apache: server config, virtual host · nginx: http, server

Set internal fetcher timeout in milliseconds

FetchHttps

Syntax: ModPagespeedFetchHttps value (Apache) · pagespeed FetchHttps value; (nginx)
Default: enable
Context: Apache: server config, virtual host · nginx: http, server

Controls direct fetching of HTTPS resources. Value is comma-separated list of keywords: enable,disable,allow_self_signed,allow_unknown_certificate_authority,allow_certificate_not_yet_valid

FetchProxy

Syntax: ModPagespeedFetchProxy value (Apache) · pagespeed FetchProxy value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Set the fetch proxy

FetchWithGzip

Syntax: ModPagespeedFetchWithGzip on|off (Apache) · pagespeed FetchWithGzip on|off; (nginx)
Default: off
Context: Apache: server config, virtual host (tolerated) · nginx: http

Request http content from origin servers using gzip

NativeFetcherMaxKeepaliveRequests

Syntax: pagespeed NativeFetcherMaxKeepaliveRequests number; (nginx)
Default: —
Context: nginx: http
Platform: nginx only

Maximum number of requests the native fetcher sends over one keep-alive connection before it opens a new one (a positive integer).

RateLimitBackgroundFetches

Syntax: ModPagespeedRateLimitBackgroundFetches on|off (Apache) · pagespeed RateLimitBackgroundFetches on|off; (nginx)
Default: on
Context: Apache: server config, virtual host · nginx: http, server

Rate-limit the number of background HTTP fetches done at once

SlurpDirectory

Syntax: ModPagespeedSlurpDirectory value (Apache) · pagespeed SlurpDirectory value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Directory from which to read slurped resources

SlurpFlushLimit

Syntax: ModPagespeedSlurpFlushLimit number (Apache) · pagespeed SlurpFlushLimit number; (nginx)
Default: 0
Context: Apache: server config, virtual host · nginx: http, server

Set the maximum byte size for the slurped content to hold before a flush

SlurpReadOnly

Syntax: ModPagespeedSlurpReadOnly on|off (Apache) · pagespeed SlurpReadOnly on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Only read from the slurped directory, fail to fetch URLs not already in the slurped directory

SslCertDirectory

Syntax: ModPagespeedSslCertDirectory value (Apache) · pagespeed SslCertDirectory value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

Directory to find SSL certificates.

SslCertFile

Syntax: ModPagespeedSslCertFile value (Apache) · pagespeed SslCertFile value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

File with SSL certificates.

TestProxy

Syntax: ModPagespeedTestProxy on|off (Apache) · pagespeed TestProxy on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Direct non-PageSpeed URLs to a fetcher, acting as a simple proxy. Meant for test use only

TestProxySlurp

Syntax: ModPagespeedTestProxySlurp value (Apache) · pagespeed TestProxySlurp value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host · nginx: http, server

If set, the fetcher used by the TestProxy mode will be a readonly slurp fetcher from the given directory

UseNativeFetcher

Syntax: pagespeed UseNativeFetcher on|off; (nginx)
Default: —
Context: nginx: http
Platform: nginx only

Use nginx’s own event-driven fetcher for the resource fetches the module makes, instead of the built-in serf fetcher.

Settable in the http block only. The native fetcher handles HTTP and HTTPS fetches.

HTML rewriting and page hints

AmpLinkPattern, BeaconReinstrumentTimeSec, BeaconUrl, EnableExtendedInstrumentation, FlushBufferLimitBytes, FlushHtml, FollowFlushes, IdleFlushTimeMs, LowercaseHtmlNames, MaxHtmlParseBytes, RetainComment

AmpLinkPattern

Syntax: pagespeed AmpLinkPattern value; (nginx)
Default: (empty)
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

BeaconReinstrumentTimeSec

Syntax: ModPagespeedBeaconReinstrumentTimeSec number (Apache) · pagespeed BeaconReinstrumentTimeSec number; (nginx)
Default: 5
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

How often (in seconds) to reinstrument pages with beacons. This is used for both critical image beaconing, and for the prioritize_critical_css filter.

BeaconUrl

Syntax: ModPagespeedBeaconUrl value (Apache) · pagespeed BeaconUrl value; (nginx)
Default: /mod_pagespeed_beacon
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

URL for beacon callback injected by add_instrumentation.

EnableExtendedInstrumentation

Syntax: ModPagespeedEnableExtendedInstrumentation on|off (Apache) · pagespeed EnableExtendedInstrumentation on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

If set to true, addition instrumentation js is added to that page that the beacon can collect more information.

FlushBufferLimitBytes

Syntax: pagespeed FlushBufferLimitBytes number; (nginx)
Default: 102400
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

FlushHtml

Syntax: ModPagespeedFlushHtml on|off (Apache) · pagespeed FlushHtml on|off; (nginx)
Default: off
Context: Apache: server config, virtual host · nginx: http, server

Enable auto-flush heuristics for HTML in full proxy mode

FollowFlushes

Syntax: ModPagespeedFollowFlushes on|off (Apache) · pagespeed FollowFlushes on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Attempt to mirror incoming flushes for html streams in the output when ProxyFetch is used.

IdleFlushTimeMs

Syntax: pagespeed IdleFlushTimeMs number; (nginx)
Default: 10
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

LowercaseHtmlNames

Syntax: ModPagespeedLowercaseHtmlNames on|off (Apache) · pagespeed LowercaseHtmlNames on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Lowercase tag and attribute names for HTML.

When enabled, HTML tag and attribute names are lowercased during parsing.

MaxHtmlParseBytes

Syntax: ModPagespeedMaxHtmlParseBytes number (Apache) · pagespeed MaxHtmlParseBytes number; (nginx)
Default: -1
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Maximum number of bytes of HTML that we parse, before redirecting to ?ModPagespeed=off

RetainComment

Syntax: ModPagespeedRetainComment wildcard (Apache) · pagespeed RetainComment wildcard; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Retain HTML comments matching wildcard, even with remove_comments enabled

Threads and limits

NumExpensiveRewriteThreads, NumRewriteThreads

NumExpensiveRewriteThreads

Syntax: ModPagespeedNumExpensiveRewriteThreads auto|number (Apache) · pagespeed NumExpensiveRewriteThreads auto|number; (nginx)
Default: —
Context: Apache: server config · nginx: http

Threads per process for heavy optimization work such as image transcoding. auto (or 0) sizes the pool from the CPUs the process may use; a positive integer sets it exactly.

Global, like NumRewriteThreads. See Optimization threads.

NumRewriteThreads

Syntax: ModPagespeedNumRewriteThreads auto|number (Apache) · pagespeed NumRewriteThreads auto|number; (nginx)
Default: —
Context: Apache: server config · nginx: http

Threads per process for short, latency-sensitive optimization work. auto (or 0) sizes the pool from the CPUs the process may use; a positive integer sets it exactly.

Global: set it once per server, not per virtual host or location. How auto resolves per server, and when to override it, is in Optimization threads.

Experiments and analytics

AnalyticsID, ContentExperimentID, ContentExperimentVariantID, EnrollExperiment, ExperimentCookieDurationMs, ExperimentSlot, ExperimentSpec, ExperimentVariable, IncreaseSpeedTracking, Noop, RunExperiment

AnalyticsID

Syntax: ModPagespeedAnalyticsID value (Apache) · pagespeed AnalyticsID value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Google Analytics ID to use on site.

ContentExperimentID

Syntax: ModPagespeedContentExperimentID value (Apache) · pagespeed ContentExperimentID value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Which Google Analytics content experiment to log to.

ContentExperimentVariantID

Syntax: ModPagespeedContentExperimentVariantID value (Apache) · pagespeed ContentExperimentVariantID value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Which Google Analytics content experiment variant to log to.

EnrollExperiment

Syntax: ModPagespeedEnrollExperiment number (Apache) · pagespeed EnrollExperiment number; (nginx)
Default: -2
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Assign users to a specific experiment setting.

ExperimentCookieDurationMs

Syntax: pagespeed ExperimentCookieDurationMs number; (nginx)
Default: 604800000
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ExperimentSlot

Syntax: pagespeed ExperimentSlot number; (nginx)
Default: 1
Context: nginx: http, server, location
Platform: nginx only

The module source carries no help text for this option.

ExperimentSpec

Syntax: ModPagespeedExperimentSpec spec (Apache) · pagespeed ExperimentSpec spec; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Configuration for one side of an experiment in the form: ‘id= ;enabled= ;disabled= ;ga= ;percent= …’

ExperimentVariable

Syntax: ModPagespeedExperimentVariable slot (Apache) · pagespeed ExperimentVariable slot; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Specify the custom variable slot with which to run experiments.Defaults to 1.

IncreaseSpeedTracking

Syntax: ModPagespeedIncreaseSpeedTracking on|off (Apache) · pagespeed IncreaseSpeedTracking on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Increase the percentage of sites that have Google Analytics page speed tracking

Noop

Syntax: ModPagespeedNoop number (Apache) · pagespeed Noop number; (nginx)
Default: 0
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Meaningless integer option for browser cache-busting in query-params

RunExperiment

Syntax: ModPagespeedRunExperiment on|off (Apache) · pagespeed RunExperiment on|off; (nginx)
Default: off
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Run an experiment to test the effectiveness of rewriters.

Deprecated and ignored

AllowVaryOn, CollectRefererStatistics, DisableForBots, DistributedRewriteKey, DistributedRewriteServers, DistributedRewriteTimeoutMs, DistributeFetches, ExperimentalCentralControllerPort, ExperimentalPopularityContestMaxInFlight, ExperimentalPopularityContestMaxQueueSize, FetchFromModSpdy, FileCacheCleanIntervalMs, FileCacheInodeLimit, GeneratedFilePrefix, HashRefererStatistics, If, ImageWebpRecompressionQuality, ImageWebpRecompressionQualityForSmallScreens, ImgInlineMaxBytes, ImgMaxRewritesAtOnce, InheritVHostConfig, MaxPrefetchJsElements, NumShards, PrivateNotVaryForIE, RefererStatisticsOutputLevel, StatisticsLoggingFile, UrlPrefix, UseExperimentalJsMinifier

AllowVaryOn

Syntax: ModPagespeedAllowVaryOn value (Apache) · pagespeed AllowVaryOn value; (nginx)
Default: (empty)
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Deprecated and ignored: in-place optimization no longer varies its output by request header.

CollectRefererStatistics

Syntax: ModPagespeedCollectRefererStatistics value (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess
Platform: Apache only

Removed option; the name is still accepted and ignored.

DisableForBots

Syntax: ModPagespeedDisableForBots value (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess
Platform: Apache only

Removed option; the name is still accepted and ignored.

DistributedRewriteKey

Syntax: ModPagespeedDistributedRewriteKey value (Apache) · pagespeed DistributedRewriteKey value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

DistributedRewriteServers

Syntax: ModPagespeedDistributedRewriteServers value (Apache) · pagespeed DistributedRewriteServers value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

DistributedRewriteTimeoutMs

Syntax: ModPagespeedDistributedRewriteTimeoutMs value (Apache) · pagespeed DistributedRewriteTimeoutMs value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

DistributeFetches

Syntax: ModPagespeedDistributeFetches value (Apache) · pagespeed DistributeFetches value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

ExperimentalCentralControllerPort

Syntax: ModPagespeedExperimentalCentralControllerPort value (Apache) · pagespeed ExperimentalCentralControllerPort value; (nginx)
Default: (empty)
Context: Apache: server config · nginx: http

Deprecated and ignored: the experimental gRPC central controller was removed

ExperimentalPopularityContestMaxInFlight

Syntax: ModPagespeedExperimentalPopularityContestMaxInFlight number (Apache) · pagespeed ExperimentalPopularityContestMaxInFlight number; (nginx)
Default: 10
Context: Apache: server config · nginx: http

Deprecated and ignored: the experimental gRPC central controller was removed

ExperimentalPopularityContestMaxQueueSize

Syntax: ModPagespeedExperimentalPopularityContestMaxQueueSize number (Apache) · pagespeed ExperimentalPopularityContestMaxQueueSize number; (nginx)
Default: 1000
Context: Apache: server config · nginx: http

Deprecated and ignored: the experimental gRPC central controller was removed

FetchFromModSpdy

Syntax: ModPagespeedFetchFromModSpdy value (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Removed option; the name is still accepted and ignored.

FileCacheCleanIntervalMs

Syntax: ModPagespeedFileCacheCleanIntervalMs value (Apache) · pagespeed FileCacheCleanIntervalMs value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

FileCacheInodeLimit

Syntax: ModPagespeedFileCacheInodeLimit value (Apache) · pagespeed FileCacheInodeLimit value; (nginx)
Default: —
Context: Apache: server config, virtual host · nginx: http, server

Removed option; the name is still accepted and ignored.

GeneratedFilePrefix

Syntax: ModPagespeedGeneratedFilePrefix value (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Removed option; the name is still accepted and ignored.

HashRefererStatistics

Syntax: ModPagespeedHashRefererStatistics value (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess
Platform: Apache only

Removed option; the name is still accepted and ignored.

If

Syntax: <ModPagespeedIf spdy|!spdy> (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Conditionally apply some mod_pagespeed options. Possible arguments: spdy, !spdy

ImageWebpRecompressionQuality

Syntax: ModPagespeedImageWebpRecompressionQuality number (Apache) · pagespeed ImageWebpRecompressionQuality number; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Former name of WebpRecompressionQuality; accepted and mapped to it.

ImageWebpRecompressionQualityForSmallScreens

Syntax: ModPagespeedImageWebpRecompressionQualityForSmallScreens number (Apache) · pagespeed ImageWebpRecompressionQualityForSmallScreens number; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location · also per request (query parameter)

Former name of WebpRecompressionQualityForSmallScreens; accepted and mapped to it.

ImgInlineMaxBytes

Syntax: ModPagespeedImgInlineMaxBytes number (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · also per request (query parameter)
Platform: Apache only

Former name of ImageInlineMaxBytes; accepted and mapped to it.

ImgMaxRewritesAtOnce

Syntax: ModPagespeedImgMaxRewritesAtOnce number (Apache)
Default: —
Context: Apache: server config, virtual host (tolerated)
Platform: Apache only

Former name of ImageMaxRewritesAtOnce; accepted and mapped to it.

InheritVHostConfig

Syntax: ModPagespeedInheritVHostConfig value (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Removed option; the name is still accepted and ignored.

MaxPrefetchJsElements

Syntax: ModPagespeedMaxPrefetchJsElements value (Apache) · pagespeed MaxPrefetchJsElements value; (nginx)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Removed option; the name is still accepted and ignored.

NumShards

Syntax: ModPagespeedNumShards value (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Removed option; the name is still accepted and ignored.

PrivateNotVaryForIE

Syntax: ModPagespeedPrivateNotVaryForIE on|off (Apache) · pagespeed PrivateNotVaryForIE on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Deprecated and ignored: in-place optimized resources are no longer browser-dependent, so they are never served as Cache-Control: private and never carry a Vary header.

RefererStatisticsOutputLevel

Syntax: ModPagespeedRefererStatisticsOutputLevel value (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess
Platform: Apache only

Removed option; the name is still accepted and ignored.

StatisticsLoggingFile

Syntax: ModPagespeedStatisticsLoggingFile value (Apache)
Default: —
Context: Apache: server config, virtual host, directory, .htaccess
Platform: Apache only

Removed option; the name is still accepted and ignored.

UrlPrefix

Syntax: ModPagespeedUrlPrefix value (Apache)
Default: —
Context: Apache: server config, virtual host
Platform: Apache only

Removed option; the name is still accepted and ignored.

UseExperimentalJsMinifier

Syntax: ModPagespeedUseExperimentalJsMinifier on|off (Apache) · pagespeed UseExperimentalJsMinifier on|off; (nginx)
Default: on
Context: Apache: server config, virtual host, directory, .htaccess · nginx: http, server, location

Deprecated and ignored: the legacy JavaScript minifier was removed; the tokenizer-based minifier is the only JavaScript minifier

Deprecated since v1.15.0+r21: the tokenizer-based minifier is the only JavaScript minifier. The directive is accepted for compatibility, ignored, and logs a deprecation warning at configuration load. Remove it from your configuration.

Optimization threads

Optimization work runs on two thread pools, separate from the threads that serve requests. The rewrite pool handles short, latency-sensitive bookkeeping; the expensive rewrite pool handles heavy CPU work such as image transcoding, so a large image cannot hold up everything else. This is the in-process module’s own thread configuration; the optimizer worker’s --num-threads and --ram-cache-size flags are a different setting, on the worker page.

In v1.15.0+r21 and later both pools size themselves. NumRewriteThreads and NumExpensiveRewriteThreads default to auto, and mod_pagespeed resolves them at startup by:

Taking the CPUs the process is actually permitted to use — not the host’s core count. A CPU quota (a container limit or a systemd unit) and a CPU affinity mask both count. A 2-CPU container on a 64-core host sees 2.
Allowing optimization at most half of those.
Dividing by the number of peer processes the server is configured to run, because each process builds its own pools. Without this step a server with many children would multiply its thread count by the number of children.
Giving the result to each pool, never fewer than one thread.

The resolved counts, and the numbers they were derived from, are written to the error log at startup.

What this means per server

Apache reports its configured child-process ceiling, so the divisor is real: MaxRequestWorkers / ThreadsPerChild on worker and event, and MaxRequestWorkers on prefork — in both cases capped by ServerLimit. If you have lowered ServerLimit, that is the number in effect, not the division.

A stock event configuration allows 400 workers at 25 threads per child, so the divisor is 16 and a server resolves to one thread per pool unless it has a great many cores. That is the intended answer: the ceiling counts children the server is allowed to start, and sizing each child as though it were alone on the machine is what oversubscribes it. A server deliberately configured with few children on a many-core machine gets proportionally more.

prefork is not threaded and resolves to one thread per pool, as it always has.

nginx does not yet report a process count to the module, so it resolves to one thread per pool and logs that it fell back. It never assumes a larger divisor: guessing high would silently oversubscribe the machine, which is worse than being conservative.

This is unchanged from earlier releases. If you have set NumRewriteThreads or NumExpensiveRewriteThreads explicitly, your values continue to apply exactly as before.

The IIS module sizes its own pools and does not yet consult these directives. Its behaviour is unchanged in this release. See IIS tuning.

Setting the counts explicitly

An explicit positive value overrides the computed one entirely.

Value	Effect
`auto`	Resolve as described above. This is the default.
`0`	An alias for `auto`.
positive integer	Use exactly this many threads per process, ignoring the computation.
negative	Rejected when the configuration is read.

A negative value is rejected at configuration-read time rather than being clamped, which on Apache means the server does not start. Very large explicit values are capped, with a warning naming both the value you asked for and the value in effect.

ModPagespeedNumRewriteThreads 4
ModPagespeedNumExpensiveRewriteThreads 4

pagespeed NumRewriteThreads 4;
pagespeed NumExpensiveRewriteThreads 4;

Both directives are global. They cannot be set per virtual host or per location: the pools are built once per process, before any virtual host is consulted.

When to change them

Most servers should leave these alone. Reach for them when the log line at startup shows a resolved count that does not match your deployment — most often a single-process server on a many-core machine, or a server whose configured child ceiling is far above the number of children it will really run.

If you raise them, watch request latency rather than only optimization throughput. The reason optimization is capped at half the machine is that the remaining half is serving traffic.

URL segment length limits

MaxSegmentLength sets the maximum length (in characters) of any single URL segment — the text between two / separators — that the module will produce when it combines or rewrites resources.

Apache servers historically capped URL segments at about 250 characters per segment. mod_pagespeed circumvents that limit when running under Apache, but intermediate proxies or CDNs in front of your origin may re-impose it. If a downstream component rejects long .pagespeed. URLs, lower this value so mod_pagespeed produces shorter combined URLs.

pagespeed MaxSegmentLength 250;

ModPagespeedMaxSegmentLength 250

pagespeed MaxSegmentLength 250

This directive applies only to the URLs mod_pagespeed generates (for example, when combining CSS or JavaScript). It does not limit which inbound request URLs the module will rewrite.

Behind a reverse proxy

When mod_pagespeed runs behind a reverse proxy (such as nginx, Varnish, or a CDN), keep the following in mind:

The proxy must forward the original Host header to the backend so that mod_pagespeed generates correct URLs for optimized resources.
If the proxy terminates TLS, configure mod_pagespeed to recognize the X-Forwarded-Proto header (RespectXForwardedProto) so that it generates https:// URLs for optimized resources. See HTTPS configuration for the details.
Ensure that .pagespeed. resource URLs are routed to the backend running mod_pagespeed. The proxy must not cache these resources independently unless you configure cache lifetimes carefully.
If the proxy strips or modifies response headers, verify that mod_pagespeed’s X-Mod-Pagespeed or X-Page-Speed header and Cache-Control directives pass through intact.

Frequently asked questions

Where is the mod_pagespeed configuration file?

Apache reads pagespeed.conf from /etc/apache2/mods-available/ (Debian, Ubuntu) or /etc/httpd/conf.d/ (RHEL, AlmaLinux, Rocky); nginx reads pagespeed directives from nginx.conf, in the http, server or location block; IIS reads pagespeed.config from the site root or %ProgramData%\We-Amp\PageSpeed\.

What is the minimal working configuration?

On Apache, ModPagespeed on and a writable ModPagespeedFileCachePath; the packaged pagespeed.conf already sets both. On nginx, load_module modules/ngx_pagespeed_module.so;, pagespeed on; and pagespeed FileCachePath /var/cache/ngx_pagespeed; in the server block, plus the three location blocks that let the module serve its own resources. On IIS, pagespeed on in pagespeed.config.

How do I write the same directive for Apache, nginx and IIS?

Prefix the directive name with ModPagespeed on Apache (ModPagespeedEnableFilters rewrite_images); on nginx write pagespeed followed by the name and a semicolon (pagespeed EnableFilters rewrite_images;); on IIS use the nginx form without the semicolon in pagespeed.config.

How do I turn mod_pagespeed off for one path?

Scope the switch: ModPagespeed off inside a <Location> or <Directory> block on Apache, pagespeed off; inside a location block on nginx, or a Disallow directive for a URL wildcard on any server.