> it is open source

Not exactly. The clients are open source, but the central server isn't. See https://github.com/keybase/client/issues/6374. It might be possible to reverse engineer the server, but it would be a lot more involved than just forking the project.

That's unfortunate. I assume Zoom would have no interest in open sourcing the server software now that they've paid for the cryptographic expertise and code, but I think the previous owners might have been willing to... surprised they never did, maybe they decided they'd never get bought if they did.

A shame, it seemed to work really well. Maybe Zoom will be willing to take my money to be a DropBox end-to-end encrypted cloud sync service instead, they seem to be fairly on the ball with responding to complaints and that they decided it was worth buying Keybase to improve their service maybe they'll come out alright.

Wishful thinking maybe =)

The best scenario would be if this led to keybase open-sourcing the server as well. I have no idea how likely that is.

Is the server open source? I know that the client is, but I haven’t found sources for the backend.

It's not: https://github.com/keybase/client/issues/6374

What was the main difference with this a drop box though? It's encrypted?

The data is stored after encryption by client which are open source (and by using boring© crypto schemes).