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There are many things you have to do/consider when you want to enable HTTP compression on IIS 6.0 (Windows Server 2003).

Can somebody please provide a comprehensive list of the actions you have to take in order to enable HTTP compression properly?

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up vote 12 down vote accepted


To verify that compression works, you could use Firefox with Firebug and YSlow plugins, they will show compression status for each component (html, javascript, css).

Also, in order to test each compression method (gzip/deflate) you could alter the "network.http.accept-encoding" preference in Firefox (default value is "gzip,deflate")

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you might also want to check… if you have appPool configured to run under a different account. – Vivek Kumbhar May 13 '10 at 23:22

Does anyone know how you TEST if your IIS6 server is sending zipped content?

Is there a "test your website" site out there that can tell you??

Can you use Firefox to tell you (firebug or some other plug in?)


Using YSlow with FireBug. Click on the "components" tab and it shows raw and gzipped sizes.

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YOu can use the Firefox Firebug extension (network tab). It shows you the details of the server's response. If you're using a proxy be sure the proxy doesn't "swallow" the compression. – splattne Apr 30 '09 at 13:28
Or use Fiddler ( for IE. – splattne Apr 30 '09 at 13:29
check my updated answer above – alexandrul Apr 30 '09 at 17:07

I played around with getting this set-up on our server (IIS 6) and while enabling it was fairly simple, it didn't give us as much control over it as I needed. I ended up purchasing httpZip from port80 Software. It made it trivial to enable and configure it. It looks like IIS 7 is much better about this.

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I used this walkthrough to setup HTTP Compression (gzip and deflate) on IIS 6. I used this metabase.xml example to tweak my configuration for best results.

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