Where does Chrome store extensions?

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. (If you have several browser profiles set up in Chrome, you will want to view the chrome://version/ page from the profile where the extension is installed.)

Examples

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

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

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.