How to check if responses are gzipped

Compressing content is important. It improves the download time and decreases the costs of traffic. 
When you want to check if content is compressed, you have to look at the content encoding of the response, and to check if the content length changes between compressed and uncompressed content. 


For example, this is a compressed object, notice the Content-Encoding header and the object size. 

>curl -I http://edition.cnn.com/ --compressed
HTTP/1.1 200 OK
access-control-allow-origin: *
cache-control: max-age=60
Content-Encoding: gzip
Content-Type: text/html; charset=utf-8
....
Content-Length: 30340
....

And this is the same object, uncompressed. 

>curl -I http://edition.cnn.com/
HTTP/1.1 200 OK
access-control-allow-origin: *
cache-control: max-age=60
Content-Type: text/html; charset=utf-8
....
Content-Length: 137752
....