OK, I’ve been looking at trying to find a replacement for a Mozilla addon that is no longer supported for quantum.
I found a perfectly serviceable, if a bit different, addon in the Chrome store,
I imported it over using Chrome Store Foxified, and some important features got left by the wayside, but I found that a simple fix reactivated them.
I have created, and signed, a personal copy for me, but I am concerned about the IP issues related to putting it up for approval on AMO, because I have been unable to contact the developer. (The app has not been updated since 2013)
While I have made changes to the program, it is literally just replacing one line in the manifest program, so I on a moral and legal level, it is still the original author’s.
I am pretty sure that there are a more than a few users (there are 1700 users for the old, unsupported app on AMO).
Unfortunately, I cannot determine from the page, or the the contents of the CRX file, what license it has been released under.