Oh, I was thinking about this upon typing my message for the first time, but then forgot it upon retyping (my browser was being erratic). Thanks for the note.

At least parts of the server are open for a long time though[1], and they also recently exchanged some stuff into WebRTC. Could anybody clarify what part of it is still nonfree?

[1] https://github.com/whispersystems/Signal-Server/