Performance headers generator

headergen.php is a script to generate assets with a combination of headers and other characteristics.

It uses path info for configuration.

• headergen.php/png/image.png - png creates png image. Formats supported: png, jpg, gif, ico, css, js
• headergen.php/png/3s/image.png - 3s adds 3 seconds to the load time
• headergen.php/png/expires/image.png - expires adds long-term expires header
• headergen.php/png/lastmod/image.png - lastmod adds last-modified header and responds with 304 if if-modified-since request was sent
• headergen.php/png/3s/lastmod/expires/image.png - you can also combine them all in one URL to have them all set (except for the content types)

Last portion and query string are completely ignored so do whatever you need with them to please tools and browsers.

A few examples

Pages with 200, 304 and infinite expires

Compare 3 version of the same page:

• 200.html - page with all assets returning 200 error code without Last-modified header so browsers download them every time.
• lastmod.html - same page with all assets returning Last-modified header and replying with 304 Not Modified so browsers do not download asset bodies every time.
• expires.html - same page with infinite Expires header set so browsers do not re-request assets (until they are purged from browser cache).

Timings for repeat view using WebPageTest.org

Waterfall diagrams for repeat view (scaled to match the time)

200.html

lastmod.html

expires.html