Doesn't work with Firefox. I just switched back to Firefox from the Opera browser; the bookmark upload from Opera seemed to go smoothly and quickly. But the sync just hangs on Firefox. When trying to merge bookmarks I get to the screen that says "please be patient, this should take 10 to 40 seconds to complete" or something like that, and it does... nothing. I just get the little wheel spinning around and around. Thinking that maybe it was just slow because I have so many bookmarks, I've left it running for as long as a half hour. Went back and it was still stuck there.

I've read some of the reviews that seemed to be good written by other Firefox users; and the most recent ones that, like me, said it didn't work. Apparently the extension needs to be updated to be compatible with the new Firefox 57.Guess I'll look around for another solution to porting my Opera bookmarks to FF.