How to view-source of a Chrome extension

how-to-view-source-of-chrome-extension.md

Option 1: Command-line download extension as zip and extract

extension_id=jifpbeccnghkjeaalbbjmodiffmgedin   # change this ID
curl -L -o "$extension_id.zip" "https://clients2.google.com/service/update2/crx?response=redirect&os=mac&arch=x86-64&nacl_arch=x86-64&prod=chromecrx&prodchannel=stable&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc" 
unzip -d "$extension_id-source" "$extension_id.zip"

Thx to crxviewer for the magic download URL.

Option 2: Use the CRX Viewer website

https://robwu.nl/crxviewer/

Option 3: Use the CRX Viewer extension

The Chrome extension source viewer is open source (github repo) and makes this super easy.

Option 3: View source of locally installed extension

1. Find your Chrome local profile directory. Open chrome://version/ and find the "Profile Path:` field. Open that folder up.
2. Open the Extensions/ subfolder
3. All your extensions are here, with typically readable source.

Mapping between locally installed extension IDs and names

• On about:extensions, turn on Developer Mode and you'll see IDs under each entry
• Inside the Extensions/ folders, the manifest.json has a readable name field

When using the above parameters for the request URL the API returns an empty response body along with an HTTP 204 status code.

$ extension_id=jifpbeccnghkjeaalbbjmodiffmgedin
$ curl --write-out '%{http_code}\n' "https://clients2.google.com/service/update2/crx?response=redirect&os=mac&arch=x86-64&nacl_arch=x86-64&prod=chromecrx&prodchannel=stable&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc"
204

Adding acceptformat=crx3 to the request URL returns the extension.

$ curl --output "$extension_id.crx" --silent --location "https://clients2.google.com/service/update2/crx?response=redirect&os=mac&arch=x86-64&nacl_arch=x86-64&prod=chromecrx&prodchannel=stable&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc&acceptformat=crx3"

$ file "$extension_id.crx"
jifpbeccnghkjeaalbbjmodiffmgedin.crx: Google Chrome extension, version 3

The SHA-256 checksum of the downloaded file matches the value returned by the API.

$ sha256sum "$extension_id.crx"
92c3ce80364f17e54dbc9332021d9368be025bffbbe0a788e055129af2fc6853  jifpbeccnghkjeaalbbjmodiffmgedin.crx

$ curl --silent --location --output "$extension_id.xml" "https://clients2.google.com/service/update2/crx?os=mac&arch=x86-64&nacl_arch=x86-64&prod=chromecrx&prodchannel=stable&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc&acceptformat=crx3"

$ xml sel -N x="http://www.google.com/update2/response" -t -v "//x:updatecheck/@hash_sha256"  -n "$extension_id.xml"
92c3ce80364f17e54dbc9332021d9368be025bffbbe0a788e055129af2fc6853

Only response, prodversion, x and acceptformat seem to be mandatory parameters, at least a request with only those results in an identical file.

$ curl --output "$extension_id.crx" --silent --location "https://clients2.google.com/service/update2/crx?response=redirect&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc&acceptformat=crx3"

$ sha256sum "$extension_id.crx"
92c3ce80364f17e54dbc9332021d9368be025bffbbe0a788e055129af2fc6853  jifpbeccnghkjeaalbbjmodiffmgedin.crx

It seems further that prodversion can be any value >= 32.

I ran into the same issue using the Swipe Well extension (ID: phoibianbflfapemikjhjjohoobljlgd) and the above from @stefanschmidt resolved the problem.

Please add a button to the direct link to the CRX file

Thanks! I used Option 4, it needs some work to find the correct folder, but if you just installed the plugin, just sort by folder modified date and pick the most recently modified one that is not Temp. By the way, Option 4 is incorrectly named "Option 3", so there are two "Option 3".

Thanks Paul!