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mod_pagespeed 1.15 — Cyclone Cache, modernized optimizations, IIS + .NET support, and six years of security updates

Optimize for bandwidth

Caching

Optimizes resources in place without changing their URLs — safe for any cache.

Filter rewrite_css,rewrite_javascript,rewrite_images · Filter docs

A mod_pagespeed 1.15 filter. ModPageSpeed 2.0 applies it as part of one always-on pipeline, not as a separate switch.

Original Open in new tab
Optimized Open in new tab

Both frames render identically — that's the goal. The win is in the bytes and requests below, not the look. They're served live by mod_pagespeed 1.15 on demo-httpd-1.1.modpagespeed.com; the optimized frame applies only this filter. Right after a cache purge it may briefly match the original while the worker rewrites it — reload to see the result.

Measured impact

This filter changes how the page is structured or delivered, not its size — so there's no byte or request reduction to chart. The change shows in the source diff below.

What changed in the source

The page's HTML, before and after this filter. Red lines are removed, green lines are added. 

                
                  

                      … 44 unchanged lines …
                    

                        <hr>
                    

                        
                    

                        <!-- this script is external, and will be optimized without changing its url -->
                    

                      - <script src="rewrite_javascript.js"></script>
                    

                      + <script src="rewrite_javascript.js.pagespeed.jm.1o978_K0_L.js"></script>
                    

                        
                    

                        <!-- this script is inline, and will be optimized in place -->
                    

                      - <script>
                    

                      -     document.write    (    "world"    )    ;
                    

                      - </script>
                    

                      + <script>document.write("world");</script>
                    

                        
                    

                        <!-- this stylesheet is external, and will be optimized without changing its url -->
                    

                      - <link rel="stylesheet" href="styles/blue.css">
                    

                      + <link rel="stylesheet" href="styles/A.blue.css.pagespeed.cf.JgQj7wAyqo.css">
                    

                        
                    

                        <!-- this stylesheet is inline, and will be optimized in place -->
                    

                      - <style>
                    

                      -   #unused    {    background-color:    red   }
                    

                      - </style>
                    

                      + <style>#unused{background-color:red}</style>
                    

                        
                    

                        <p>
                    

                        
                    

                        <!-- This image will be converted to WebP in supporting browsers, and optimized regardless. The url won't change, but the response will be
                    

                             served with 'Vary: Accept' so it will work with proxy caches in all
                    

                             browsers. -->
                    

                      - <img src="in_place_optimize_for_browser/Puzzle.jpg">
                    

                      + <img src="in_place_optimize_for_browser/xPuzzle.jpg.pagespeed.ic.H8AYL0e7U2.webp">

Run this on your own site

This is one of 49 filters mod_pagespeed 1.15 applies in place — self-hosted on Apache, nginx, and IIS. Install and run it: it optimizes right away and adds an X-PageSpeed-Warn: unlicensed header until you license it. Production use requires a commercial license — but the software never locks you out.

Download & run
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