I would be a bit suspicious towards Mattermost, but maybe with a warning and for small private groups it could be ok. mattermost/mattermost#6320

I don't think the suite is "100% opensource", from what I gather it's only some components to interact with Kopano's suite of web apps that are: https://stash.kopano.io/projects

For example, I could not find the source code for Kopano Meet.

My bad, I found Kopano Meet's source code, licensed under AGPLv3: https://stash.kopano.io/projects/KWM/repos/meet/browse

Documentation for Kopano Meet: https://documentation.kopano.io/kopano_meet_manual/installation.html

I focus on Meet because instant messenger and video calls are a keen interest of mine, as they are a particularly difficult and demanded use case nowadays ;-)

Ok so Kopano Meet seems very interesting, it does what Jitsi Meet should by directly connecting the peers together and end-to-end encrypting all communications, without decrypting on server. In fact, they clearly state that communications never go through the server, it's all through WebRTC. I think it's a worthy addition, at first as a "Worth Mentioning" at first but if we can gather more infos and it gets more established then it could potentially become a recommendation.

@Raviu56 do you have any info about what kind of encryption is used more technically? We can likely find from the source code otherwise although more cumbersome (this info is not in the readme).

Also, they claim that the app supports an unlimited amount of participants, in the free version. Contrary to, surprisingly, their starting paid plan which only allows for about 500 users max. I guess this is because the free version uses peer-to-peer only, so that their server does not get overloaded like Jitsi Meet can, and so the only limitation is whether the participants have an internet bandwidth large enough to sustain the streams from a number of participants. The paid plans offer a Jitsi Meet-like system with a server in the middle to balance the load.

So this adds additional credence to the statement that Kopano Meet is by default fully P2P. I would be very curious to see how well it performs with say 50 or 100 participants, something that Jitsi Meet struggles with. If Kopano Meet sustains this kind of load, it could be very useful for academic meetings.

About the Kopano "office" suite, it seems very nice for teams, but it seems complex to setup, it seems necessary to self-host or buy their subscription, I can't see a free mode (please correct me if I'm wrong).