How to unpack a chrome theme?

Question

How to unpack a packed chrome theme(*.crx)? Their FAQ states how to pack, but not how to unpack.

score 16 · Answer 1 · answered Jan 14 '16 at 22:25

16

On Mac OS X, you can use unzip to decompress the .crx file:

unzip extension.crx

Here's the result:

answered Jan 14 '16 at 22:25

Elad Nava

416
5
8

1

works on linux too – Dr.X Jun 25 '20 at 19:34
works on mac too – YMG Mar 24 '22 at 18:12

score 14 · Answer 2 · answered May 09 '10 at 03:37

14

I got the solution: apparently, a .crx file is just a renamed .zip file. Additionally, when you install it, the theme is decompressed into the chrome install directory...

answered May 09 '10 at 03:37

aviraldg

2,389
4
17
17

4

Not quite; it’s not *just* a renamed ZIP. Open one in a hex-editor and see that there is clearly a proprietary header. That said, yes, it is basically a ZIP, and can be opened in most ZIP-capable programs. I prefer [7-Zip](http://www.7-zip.org/). – Synetech Jul 13 '11 at 03:25
4

@Synetech is correct, the file header contains a public key and signature. Google's [.crx Package Format](http://developer.chrome.com/extensions/crx.html) page explains this. In practice, you should be able to extract a .crx file with `unzip`, and it will ignore the extra bytes. If you do end up needing to chop off the header first, running unzip -l will show you how many (**N+1** bytes with tail). For example: If `unzip -l` complains with **warning [file.crx]: ***306*** extra bytes at beginning or within zipfile**, then run: `tail -c +307 file.crx > /tmp/file.crx; unzip -l /tmp/file.crx` – TrinitronX Dec 13 '12 at 22:45

score 4 · Answer 3 · edited Jul 13 '11 at 02:12

4

Actually it's more than a zip. When you unzip -l you'll see a message:

warning [extension.crx]: 306 extra bytes at beginning or within zipfile

So the crx file is 306 bytes of something plus a zip archive.

edited Jul 13 '11 at 02:12

Gaff

18,569
15
57
68

answered Jul 26 '10 at 14:37

Helmut Grohne

41
1

score 3 · Answer 4 · edited Jul 13 '11 at 02:11

3

Chrome extension install directory:

Mac:

/Users/username/Library/Application Support/Google/Chrome/Default/Extensions

Windows 7:

C:\Users\username\AppData\Local\Google\Chrome\User Data\Default\Extensions

Windows XP:

C:\Documents and Settings\YourUserName\Local Settings\Application Data\Google\Chrome\User Data\Default

edited Jul 13 '11 at 02:11

Gaff

18,569
15
57
68

answered Feb 12 '11 at 20:28

JDavis

31
1

Best solution out of them all. This worked for me, none of the others did. – daviesgeek Jan 27 '12 at 17:20

score 3 · Answer 5 · edited Dec 13 '12 at 22:46

3

This video explains everything about what a .crx is. In addition to a .zip holding all the extension's resources, it includes a public key and a signature, to ensure integrity and authenticity of the file: Antony Sargent explains .crx files Hosted by: youtube.com

The details of the .crx package format are published here.

edited Dec 13 '12 at 22:46

TrinitronX

160
8

answered Jul 12 '11 at 20:28

Crow

31
1

score 0 · Answer 6 · answered May 09 '10 at 05:29

0

Yep aviraldg is right. rename it to a .zip and use your favorite extraction tool. XPIs for firefox, etc, are the same process.

answered May 09 '10 at 05:29

alpha1

1,686
1
14
18

How to unpack a chrome theme?

6 Answers6