This sounds like what Symless does with Synergy[1]. Or did -- now the repo is named "synergy-core", so they are likely also using an "open core" model now. [1]

This sounds like what Symless does with Synergy[1]. Or did -- now the repo is named "synergy-core", so they are likely also using an "open core" model now. [1]: https://github.com/symless/synergy-core https://github.com/symless/synergy-core