IISpeed alternative

IISpeed is now deprecated. Existing customers get a free license transfer to either mod_pagespeed 1.15 (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.
• AVIF, Core Web Vitals signals, and modern variant fan-out never landed.
• Customer demand consolidated on either drop-in IIS upgrades (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 1.15, shared with Apache, nginx, and Envoy.

Path 1 — mod_pagespeed 1.15 for IIS

If you have an IIS deployment and want a drop-in replacement, mod_pagespeed 1.15 has a native IIS port with the same module surface IISpeed offered. Same web.config syntax, same filters, 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 1.15 docs · 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 1.15 for IIS
Existing IISpeed install you want to keep running with security patches	mod_pagespeed 1.15 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 1.15 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, the transfer to mod_pagespeed 1.15 or to the WeAmp.PageSpeed.Sidecar NuGet package is free and processed manually. Email license@we-amp.com with your IISpeed license key. We aim to send your replacement key in about a business day.

Existing IISpeed license keys still work for the transition window 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 1.15 for IIS, and ASP.NET Core deployments should use the WeAmp.PageSpeed.Sidecar NuGet package.

How do I transfer my IISpeed license?

Email license@we-amp.com with your IISpeed license key. We aim to send your replacement key for mod_pagespeed 1.15 or the WeAmp.PageSpeed.Sidecar NuGet package in about a business day. The transfer is free.

What replaces IISpeed for IIS deployments?

mod_pagespeed 1.15 ships a native IIS module with the same web.config surface IISpeed offered — same filters, same admin console, plus security patches, current toolchain, and Cyclone Cache.

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 1.15 for IIS is the right path — it's an IIS module, no application code changes required.

Can I run both mod_pagespeed 1.15 for IIS and the WeAmp.PageSpeed.Sidecar package?

Yes. Mixed environments are supported. Both reuse the same optimization core and share an admin console.

Install and run

Install either path and it optimizes right away — an unlicensed install stays fully functional and just adds an X-PageSpeed-Warn: unlicensed response header. Production use requires a commercial license — but the software never locks you out.

• mod_pagespeed 1.15 for IIS — Download the MSI · Buy a license · 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. 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.