IISpeed alternative

IISpeed is now deprecated. Existing customers get a free license transfer to either mod_pagespeed 2.1 (native IIS port) or to the WeAmp.PageSpeed.Sidecar NuGet package for ASP.NET Core. Support continues, but bug fixes and security patches have stopped.

This page explains both forward paths.

What IISpeed was

IISpeed wrapped the mod_pagespeed optimization libraries in an IIS module (IISpeedModule.dll) that registered against the IIS request pipeline. Configuration sat in web.config under <system.webServer>. Filters, variants, and the admin console all worked the same way as the Apache and nginx ports.

Customers ran it on Windows Server 2008 R2 through 2019. The IIS module ABI stayed compatible across those releases.

Why it's deprecated

• The .NET 4 and IIS 7-era toolchain is increasingly painful to build and test against modern Windows.
• The current image pipeline (WebP variants), Core Web Vitals signals, and the newer variant fan-out never landed in the IISpeed build.
• Customer demand consolidated on either drop-in IIS replacements (where 1.15 fits) or on ASP.NET Core (where the WeAmp.PageSpeed.Sidecar NuGet package fits).
• One IIS code path is better than two. The IIS port now lives inside mod_pagespeed, shared with the Apache and nginx ports.

Path 1 — mod_pagespeed for IIS

If you have an IIS deployment and want a drop-in replacement, mod_pagespeed for IIS is a native IIS port with the same module surface IISpeed offered. Same web.config syntax, a modernized, secured filter stack with new optimizers, same admin console — plus security patches, current toolchain, and Cyclone Cache.

<!-- web.config -->
<system.webServer>
  <modules>
    <add name="ModPagespeedModule" type="ModPagespeed.IIS.Module, ModPagespeed.IIS" />
  </modules>
  <pagespeed enabled="true">
    <fileCachePath>C:\inetpub\modpagespeed\cache</fileCachePath>
  </pagespeed>
</system.webServer>

The MSI installer from the downloads page registers the module, creates the cache directory, and warm-starts the worker.

mod_pagespeed docs · IIS migration guide · Download the MSI

Path 2 — WeAmp.PageSpeed.Sidecar NuGet package for ASP.NET Core

If your stack is ASP.NET Core, IIS is no longer the natural integration point. The WeAmp.PageSpeed.Sidecar NuGet package is the GA 1.15 ASP.NET Core integration: your Kestrel app stays the public front door, and the package's bundled nginx runs on loopback behind it as the optimize-proxy:

// Program.cs
using WeAmp.PageSpeed.Sidecar;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddPageSpeed();

var app = builder.Build();
app.UsePageSpeed();
app.Run();

dotnet add package WeAmp.PageSpeed.Sidecar

The package bundles the mod_pagespeed 1.15 core (nginx 1.30.2) and starts it on loopback automatically — no IIS module registration, no web.config editing, no gacutil. It is Linux-only (linux-x64 / linux-arm64), for container and Linux deployments of ASP.NET Core.

How the integration works · NuGet package

Which path fits

Use case	Choose
Classic ASP.NET / WebForms / MVC 5 on IIS	mod_pagespeed for IIS
Existing IISpeed install you want to keep running with security patches	mod_pagespeed for IIS
ASP.NET Core 6+ on Kestrel (Linux)	WeAmp.PageSpeed.Sidecar NuGet package
Linux container deployment of an ASP.NET Core app	WeAmp.PageSpeed.Sidecar NuGet package
ASP.NET Core hosted on Windows / IIS	mod_pagespeed for IIS (the Sidecar is Linux-only)
Mixed environment (some sites on classic IIS, some on .NET Core)	Run both — they share the same core and admin console

License transfer

If you hold an IISpeed license, there is nothing to transfer: mod_pagespeed 2.1 and the WeAmp.PageSpeed.Sidecar NuGet package are free to install and run. Questions about an existing IISpeed subscription go to license@we-amp.com; the IISpeed transition window is documented at iispeed.com.

Frequently asked questions

Is IISpeed still supported?

Support continues for existing customers, but IISpeed is deprecated and bug fixes and security patches have stopped. New IIS deployments should use mod_pagespeed for IIS, and ASP.NET Core deployments should use the WeAmp.PageSpeed.Sidecar NuGet package.

I hold an IISpeed license. What do I need to do?

Nothing to move to mod_pagespeed 2.1 or the WeAmp.PageSpeed.Sidecar NuGet package — both are free to install and run. Questions about an existing IISpeed subscription go to license@we-amp.com.

What replaces IISpeed for IIS deployments?

mod_pagespeed 2.1 ships a native IIS module with the same web.config surface IISpeed offered — a modernized, secured filter stack with new optimizers, same admin console, plus security patches, current toolchain, and Cyclone Cache. The IIS package ships from the 1.15 packaging channel.

Does WeAmp.PageSpeed.Sidecar work with classic ASP.NET?

WeAmp.PageSpeed.Sidecar is for ASP.NET Core. For classic ASP.NET / WebForms / MVC 5 on IIS, mod_pagespeed for IIS is the right path — it's an IIS module, no application code changes required.

Can I run both mod_pagespeed for IIS and the WeAmp.PageSpeed.Sidecar package?

Yes. Mixed environments are supported. Both run the same mod_pagespeed core — the native IIS module and the Sidecar package (bundled nginx + ngx_pagespeed on loopback) — so they share the same filters and admin console.

Install and run

Install either path and it optimizes right away. The converged mod_pagespeed 2.1 is open source under Apache-2.0 — free in development and in production.

The IIS package ships from the 1.15 packaging channel.

• mod_pagespeed for IIS — Download the MSI · Support plans · IIS docs
• WeAmp.PageSpeed.Sidecar NuGet package — NuGet package · ASP.NET Core docs

Related

• mod_pagespeed alternative
• ngx_pagespeed alternative
• Google PageSpeed Module alternative
• Is mod_pagespeed deprecated? — what changed and what to use
• iispeed.com — transition information for existing customers
• IIS & Core Web Vitals in 2026

IIS, ASP.NET, Windows Server, and other product names are trademarks of their respective owners. mod_pagespeed is an open-source project originally developed at Google; its maintained continuation, mod_pagespeed 2.1, is developed by We-Amp B.V. Comparisons reflect publicly available information as of 2026 and are provided for evaluation; We-Amp B.V. is not affiliated with or endorsed by Microsoft Corporation or Google.