Reputation: 7321

How can I tell if my server is serving GZipped content?

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?

Upvotes: 215

Answers (8)

Mahdi Baghbani

Reputation: 58

since it's first search result in google, I'm going to edit one of the answers to include Brotli compression too, its short name is br and you can use it with curl or watch for it via F12 in browser.

for curl edited from @zoul answer:

$ curl http://example.com/ --silent --write-out "%{size_download}\n" --output /dev/null
31032
$ curl http://example.com/ --silent -H "Accept-Encoding: gzip,deflate,br" --write-out "%{size_download}\n" --output /dev/null
2553

Upvotes: 3

zoul

Reputation: 104065

It looks like one possible answer is, unsurprisingly, curl:

$ curl http://example.com/ --silent --write-out "%{size_download}\n" --output /dev/null
31032
$ curl http://example.com/ --silent -H "Accept-Encoding: gzip,deflate" --write-out "%{size_download}\n" --output /dev/null
2553

In the second case the client tells the server that it supports content encoding and you can see that the response was indeed shorter, compressed.

Upvotes: 295

pietrorea

Reputation: 898

Here's my one-liner:

curl https://google.com --silent -L -H "Accept-Encoding: gzip,deflate" --output testFile && file testFile

The file command line tool tells you what type of file it is. You should see this:

testFile: gzip compressed data, max compression, original size modulo 2^32 13926

Upvotes: 2

Software Prophets

Reputation: 2976

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.

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:

enter image description here

And the following if there IS compression:

enter image description here

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

Upvotes: 168

Krupall

Reputation: 409

In new version of chrome, Developer tools > network, you can right click on Column name, and select content-encoding option and add that column (black box in image).

and if you want to see the size of that gzip content, as @Outfast Source - than you can click on icon which is next to View (displayed as Green box in image).

so you can see which content is gzip enabled.

Upvotes: 23

Nate Symer

Reputation: 2293

I wrote this script based on the zoul's answer:

#!/bin/bash

URL=$1
PLAIN="$(curl $URL --silent --write-out "%{size_download}\n" --output /dev/null)"
GZIPPED="$(curl $URL --silent -H "Accept-Encoding: gzip,deflate" --write-out "%{size_download}\n" --output /dev/null)"

if test $PLAIN -gt $GZIPPED
then echo "supported"
else echo "unsupported"
fi

example: