mod_pagespeed 2.1: one product again

For the past year we shipped two products: mod_pagespeed 1.15, the maintained continuation of the classic module, and ModPageSpeed 2.0, a ground-up rewrite of the optimization engine. Today they are one product again.

mod_pagespeed 2.1 is the converged line: the native web-server module for Apache and nginx, with the 2.0 engine running alongside it as a separate optimizer worker. It is open source under the Apache-2.0 license — the same license the original codebase carried — and it is a drop-in for your existing configuration: 1.14 and 1.15 directives and filter names carry over.

What actually converged

The module stays. If you run mod_pagespeed today, 2.1 keeps the pagespeed-directive surface and the 1.14/1.15 filter names on its Core surface — swap the packages and your pagespeed.conf carries over. On the supported Linux deb/rpm channels the module and the pagespeed-optimizer worker install from the same signed repository at packages.modpagespeed.com.

The optimizer moved out. The heavy work — image transcoding and the rest of the rewrite pipeline — now runs in the worker, off the request path, writing optimized variants back to the Cyclone cache that the Apache module, and nginx in the reverse-proxy deployment, serve from. That worker is the ModPageSpeed 2.0 engine: the image pipeline with ML-predicted quality and SSIMULACRA2 verification, variant-aware caching, and the optimizations the rewrite was built for, now behind the module everyone already runs.

Why the architecture is worth having

A web optimizer decodes untrusted bytes: every image it recompresses and every page it parses arrived from somewhere else. In mod_pagespeed 2.1 that optimization work runs in a dedicated pagespeed-optimizer process, under its own unprivileged system user with an empty capability set, and with the Apache module or the reverse-proxy deployment the module reaches its results through the shared cache. Browser-based analysis runs in that same worker process, with the Chrome sandbox required by default.

Browser analysis and the agentic web

Browser-based analysis (critical-CSS validation, waterfall capture, visual comparison) and the agent-readability tooling that makes your pages legible to AI assistants as well as browsers run in the optimizer worker, and reach you with the Apache module or the reverse-proxy deployment.

Open source, Apache-2.0

mod_pagespeed 2.1 is open source under the Apache-2.0 license, like the original codebase — and the relicensing is retroactive, covering the predecessor lines as well. The source lives at github.com/We-Amp/mod_pagespeed. There are no editions and no usage registration, and the standard signed packages are free. What’s for sale is support and hardened, attested builds: SLA-backed plans, enterprise attestation with hardened builds, and a hoster partner program from the people who build it.

What this means for you

• Running mod_pagespeed 1.15? The line continues — 2.1 is its next release, and the upgrade is drop-in. The IIS package ships from the 1.15 packaging channel. The upgrade guide has the details.
• Running ModPageSpeed 2.0? The Docker/Helm line moves via the migration guide. The ASP.NET Core middleware continues unchanged.
• New here? Install it — two packages, your existing web server, free in development and in production.

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mod_pagespeed is an open-source project originally developed at Google. We-Amp helped build ngx_pagespeed, maintained mod_pagespeed, and drove the project’s Apache incubation throughout the Google era; mod_pagespeed 2.1 is developed by We-Amp B.V. and is not affiliated with or endorsed by Google.