Isn't often heard around HN that it's ok to charge for Open Source software ? If you don't want to pay for it, you're free to choose not to, but if others want to pay, what's in it for you?
BTW the parts of Synergy that were Open Source are still Open Source, so you're free to download those and build them yourself if you so choose.
They don’t make it very easy to do so - my understanding is that’s essentially what Barrier is (making it easy to use the open source parts of Synergy).
BTW the parts of Synergy that were Open Source are still Open Source, so you're free to download those and build them yourself if you so choose.