I can't think of a single piece of software that has cloud syncing, for free, with no option for payment.

I'm not sure who is running it (hopefully some well funded academic group), but it restores me faith in humanity a little every time I press sync and don't get CTA'd to sign up for some subscription.

Amazing tool, kudos to the devs, and if there other comes a time where payment is required, I would be happy to chip in with the above being said.