Optimize for bandwidth
CachingOptimizes 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.
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
Total bytes
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.