Barrier has been abandoned quite awhile ago. Its successor is supposed to be InputLeap, and although their GitHub repo is very active, they have yet to make a release.

I didn't even know that Synergy provided a "community" version of their app until very recently. I've paid for a license many years ago, so I've been using their 1.1x versions, which for better or worse, are still maintained along with the 3.x branch (which I've tried using but could never make it work, which is for the best because the fact they pivoted their UI to electron-based also left a bad taste in my mouth).

Edit: also, if I understand correctly, Synergy's latest versions on the 1.x branch borrows a lot from InputLeap.