I just installed teleguard because of this comment.

It's run by SwissCows, they claim it's fully encrypted with the latest/greatest tech, and comply with GDPR (and since they claim to not store user data, it's pretty simple).

It's simplistic in it's setup (not really a criticism, just a description/observation). This seems to be because (they claim) no data is stored on their servers (messages transit,and are deleted upon delivery).

If you want to use another device simultaneously, you have to backup one device, then restore it to the new device (backup requires a password). They'll then have the same history and will remain in sync, I think. So far I haven't gotten the restore to work because both devices must run the exact same version, and the Windows version isn't up to date.

I haven't found documentation on where the backup is stored, but I suspect the restore process pulls the backup from the first device.

Edit: Sync works, I'm just an idiot. When it says use your ID, they mean the code, not your Nickname. 🤦🏼‍♂️

It seems to work well, did some voice and video calls between phone and laptop, sent files, etc.