Q:

Where does Chrome store extensions?

I looked in:
C:\Documents and Settings\username\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions

for unpacked extensions, but that folder is empty for me.
For newer versions, where does Chrome store the files?

A:

Storage Location for Unpacked Extensions
Extension engine does not explicitly change their location or add a reference to its local paths, they are left in the place where there are selected from in all Operating Systems.
Ex: If i load a unpacked Extension from E:\Chrome Extension the unpacked Extension is still in the same location
Storage Location for Packed Extensions
Navigate to chrome://version/ and look for Profile Path, it is your default directory and Extensions Folder is where all the extensions, apps, themes are stored
Ex:
Windows
If my Profile Path is %userprofile%\AppData\Local\Google\Chrome\User Data\Default then my storage directory is:
C:\Users\<Your_User_Name>\AppData\Local\Google\Chrome\User Data\Default\Extensions 

Linux
~/.config/google-chrome/Default/Extensions/

MacOS
~/Library/Application\ Support/Google/Chrome/Default/Extensions

Chromium
~/.config/chromium/Default/Extensions

A:

For my Mac, extensions were here:
~/Library/Application Support/Google/Chrome/Default/Extensions/
if you go to chrome://extensions you'll find the "ID" of each extension. That is going to be a directory within Extensions directory. It is there you'll find all of the extension's files.

A:

Since chrome has come up with the multiple profiles you will not get it directly in C:\Users\<Your_User_Name>\AppData\Local\Google\Chrome\User Data\Default\Extensions but you have to first type chrome://version/ in a tab and then look out for Profile path inside that and after you reach to your profile path look for Extensions folder in it and then folder with the desired extension Id

