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

6 Answers 6

17

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

unzip extension.crx

Here's the result:

unzip result

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  • 1
    works on linux too
    – Dr.X
    Jun 25, 2020 at 19:34
  • works on mac too
    – YMG
    Mar 24, 2022 at 18:12
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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...

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  • 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.
    – Synetech
    Jul 13, 2011 at 3:25
  • 4
    @Synetech is correct, the file header contains a public key and signature. Google's .crx Package Format 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, 2012 at 22:45
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.

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
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  • Best solution out of them all. This worked for me, none of the others did.
    – daviesgeek
    Jan 27, 2012 at 17:20
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.

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

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