Re: Well, duh.
I suggest qTox for multi-platform. I don't know if it satisfies your other requirements, but maybe you could take a look and let us know?
Had a quick look.
- multi-platform, with (as far as I can see) code native to each platform
- peer to peer model seeks to avoid centralised services (not yet worked out how that hops the typical NAT port problem
- thought through in terms of what it seeks to protect
- contact discovery. Users are asked to copy a very long string to connect to others so not yet ready for your average end user. There is apparently a service that makes it easier, but there will always be a conflict between deniability and ease of interaction.
- not a commercial entity. If something doesn't work or needs fixing, having a contractual relationship means you have a better argument in getting things fixed. For smaller environments it also offers a route to support - I know free projects can sometimes offer very good ad-hoc support but for use in a commercial setting that's not good enough. The flipside is that that obviously prevents any financial blackmail from subverting the platform
- too new to have usable UIs (uTox as well as qTox for macos are barely functional, the iOS app is a little bit better).
Overall, the impression I get is that it would be too immature to use for what we're doing. I must try to get hold of Moxie to see what we could do with Signal.