How can I tell if my server is serving GZipped con

Question

I have a webapp on a NGinx server. I set gzip on in the conf file and now I'm trying to see if it works. YSlow says it's not, but 5 out of 6 websites that do the test say it is. How can I get a definite answer on this and why is there a difference in the results?

Answer 1

Update

Chrome changed the way it reports (see original answer if interested). You can tell using Developer Tools (F12). Go to the Network tab, select the file you want to examine and then look at the Headers tab on the right. If you are gzipped, then you will see that in the Content-Encoding.

In this example, slider.jpg is indeed being gzipped.

Compare that to this very page that you are on and look at a png file, you will see no such designation.

Just to be clear, it isn't because one is a jpg and one is a png. It is because one is gzipped and the other one isn't.

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Previous Answer

In Chrome, if you pull up the Developer Tools and go to the Network tab, then it will show the following if there is no compression:

And the following if there IS compression:

In other words, the same number, top and bottom, means no compression.

Answer 2

See in the response headers. In FireFox you may check with Firebug.

Content-Encoding    gzip

If server supports gzip content then this should be displayed.