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 module filter.
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 the mod_pagespeed module 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 the mod_pagespeed module applies in place — self-hosted on Apache, nginx, and IIS. Install and run it: it optimizes right away and adds an the optimized response headers shown above. Open source under the Apache License 2.0 — free in development and in production.