weblikes

 Weblikes  is a simple protocol for adding likes to pages on the open web built by Dave Winer.

The project is open source and is maintained on GitHub at https://github.com/scripting/likes.

IndieWeb examples

 * Dave Winer has been using the system on his website since at least 2018-11-10 (self-dogfooding)
 * UI example: http://scripting.com/2018/11/29.html#a211652

Criticism
While the project site describes weblikes as "outside of any silos", it relies heavily on Twitter for identity and authentication and thus is a major potential source of future failure.

The service doesn't allow the person leaving the like to keep a copy of their own data or easily find it on a site after-the-fact.