I have been using ItsAllText on Linux with the Emacs editor for a long time. When this extension became unsupported, I started searching for a replacement. I am happy with GhostText, which works well enough. Note that Emacs requires atomic-chrome in order to work with GhostText. Thank you!

I didn't give 5 stars because sometimes GT gets a bit confused and the editor unsyncs from GhostText. But it might be a problem with the editor extension.