I will update the script to only allow .css and .js extensions to be parsed which would solve this issue.

As for the expiry, 3 days is generally fine for my usage, if people want longer expiries it’s easily changed in the php script.

Thanks again.

Your tool contains a security hole, you should be careful with file_get_contents.
Now it’s possible to send something like gzip.php?f0=/etc/passwd and stole content of files from the server, for example, source code, database password, etc.

But in general, sure it’s a useful tool (if we fix the issue above) and it can be used on hostings where we cannot change server settings.
Also, I would send 1 month expires header (instead of 3 days) and I would send Last-Modified header so browsers will be able to send conditional requests.

http://thewebdevelopmentblog.com/2008/10/tip-speed-up-your-websites-using-gzip-and-merging-files/

The other methods above easier but if you can’t get it to work either look at the link above.

It can also merge your files and cache them to increase loading speed even more.

Cheers!