IISpeed has a new home — and your license comes with you
IISpeed's PageSpeed optimization for IIS is continuing under a new name: mod_pagespeed 2.1. The IIS package ships from the 1.15 packaging channel. It uses the same PageSpeed Automatic library. Your existing license transfers at no cost — nothing to repurchase, nothing to lose.
What this means for you
- 1. Your license transfers at no cost. The line is open source now, and on IIS you run mod_pagespeed 2.1. The IIS package ships from the 1.15 packaging channel. No repurchase, no key needed.
- 2. Same PageSpeed Automatic library. mod_pagespeed 2.1 uses the same PageSpeed Automatic library you already rely on, with continued updates.
- 3. No hard cutoff. IISpeed continues to work — there's no forced cutoff — and new features, bug fixes, and security patches land in mod_pagespeed 2.1.
- 4. Also available beyond IIS. mod_pagespeed 2.1 ships open source under Apache-2.0 with native modules for nginx and Apache; the same technology is available for ASP.NET Core as native middleware.
PageSpeed for IIS in 2026
Core Web Vitals optimization for IIS and ASP.NET shops
Most Core Web Vitals advice for .NET shops stops at "enable compression and ship a CDN." That moves the needle, but it leaves the work that actually shifts Largest Contentful Paint and Cumulative Layout Shift — image optimization, critical CSS, lazy loading, content negotiation — to a build step that classic ASP.NET, WebForms, and SharePoint sites rarely have. IISpeed was built to do that work at the server, transparent to the application. That library is now maintained as mod_pagespeed 2.1 for IIS. The IIS package ships from the 1.15 packaging channel. For ASP.NET Core, it ships as the WeAmp.PageSpeed.AspNetCore NuGet middleware.
Classic IIS, ASP.NET, WebForms, SharePoint
mod_pagespeed 2.1 ships a native IIS module. The IIS package ships from the 1.15 packaging channel. It incorporates IISpeed's IIS integration. Install it on Windows Server, point IIS at it, and the module rewrites responses as they leave the worker process. No application changes; no rebuilds; no CDN tier required.
mod_pagespeed 2.1 for IISASP.NET Core (.NET 8 / .NET 9)
WeAmp.PageSpeed.AspNetCore
wraps the same PageSpeed Automatic library, packaged as ASP.NET Core middleware.
One app.UsePageSpeed()
call in Program.cs
— no separate web server, no IIS dependency. Runs equally well behind
Kestrel, in containers, or on IIS as a reverse proxy.
What mod_pagespeed 2.1 does on an IIS site
Four categories of work, all applied at response time without modifying the underlying application:
-
Image optimization
JPEG and PNG recompression, WebP and AVIF variants served via content negotiation, automatic resizing to rendered dimensions. The image work alone often moves Largest Contentful Paint by seconds on image-heavy classic ASP.NET pages.
-
Critical CSS
Above-the-fold CSS is extracted and inlined; the rest is deferred. First paint stops blocking on a CSS round trip — a measurable LCP improvement on the slow Windows-shared-hosting tail.
-
Lazy loading and deferred JavaScript
Off-screen images and iframes load on demand; non-critical JavaScript moves to the end of the document. Cumulative Layout Shift and Interaction to Next Paint improve in step.
-
Content negotiation and cache
One source asset produces multiple variants (WebP/AVIF, mobile-resized, recompressed) keyed off Accept and Viewport headers. The optimized variants are cached server-side; downstream CDNs see ordinary HTTP responses.
Want the full checklist?
We wrote up the IIS Core Web Vitals workflow — what to measure, which filters move which metric, and the migration path from classic ASP.NET to ASP.NET Core middleware — as a separate article.
Read the IIS Core Web Vitals 2026 guideTransfer your license, or just install it
New to PageSpeed optimization on IIS? Here are your options.
mod_pagespeed 2.1 — IIS
The direct successor to IISpeed. Native IIS module with the same PageSpeed Automatic library, actively maintained. The IIS package ships from the 1.15 packaging channel. The right choice if you run IIS natively on Windows Server.
Download at modpagespeed.commod_pagespeed 2.1 — nginx & Apache
A modern C++23 rewrite, open source under Apache-2.0, with native modules for nginx and Apache. For .NET environments, the same optimization technology ships as native ASP.NET Core middleware.
See what's in 2.1Already have an IISpeed license? Contact us to transfer it to mod_pagespeed 2.1 at no cost. Customers of the legacy mod_pagespeed open-source builds can also read our open-source transition note.
Prefer nginx, Apache, or ASP.NET Core over the native IIS package? Ask us about moving to mod_pagespeed 2.1.
Frequently asked questions
Do I need to buy a new license?
No. Your existing IISpeed license transfers to mod_pagespeed 2.1 at no cost. Email info@we-amp.com with your license key and we confirm the transfer — handled manually, usually within a business day or two. The line is open source now, so no key is needed to keep running.
Will my IISpeed configuration still work?
mod_pagespeed 2.1 uses the same configuration directives. The IIS package ships from the 1.15 packaging channel. Most configurations will work with minimal changes. The documentation covers any differences.
When will IISpeed stop receiving updates?
There is no hard cutoff date. IISpeed continues to work, and new features and security patches land in mod_pagespeed 2.1. We recommend migrating when convenient.
What about the rest of the mod_pagespeed 2.1 line?
mod_pagespeed 2.1 is open source under Apache-2.0, with native modules for nginx and Apache. For .NET environments, the same optimization technology ships as native ASP.NET Core middleware — no web server dependency required.
Have a technical question? See the full FAQ for troubleshooting and configuration help.