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"Extensions" can be defined many ways and the fact that you have to ask this makes me think you have no idea what you'd be doing.

What is it that you're doing?
 
Ok I have uninstalled an extension from Safari and I want to find where they are in the library to see if there are any remains to it ie. the alias or something so that I can delete it completely.I didn't ask how to do anything BTW I just wanted to know the folders or suchlike they're in.
 
Ok I have uninstalled an extension from Safari and I want to find where they are in the library to see if there are any remains to it ie. the alias or something so that I can delete it completely.I didn't ask how to do anything BTW I just wanted to know the folders or suchlike they're in.

In addition to the extension itself, you will find each extension has a settings database in this users library folder.

~/Library/WebKit/com.apple.Safari/ContentExtensions
 
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