Element
FreeEmail, but for chat — an open protocol with a server you can own
The flagship client for the Matrix protocol. Like email, users on different servers can talk to each other — and you can run your own server and keep every message on your hardware. Direct messages are end-to-end encrypted by default, with groups, voice and video calls and cross-platform sync.
Why we picked it
The problem with most chat apps is not that they lack encryption — it is that you have no choice of server. Matrix aims to work the way email does: an open protocol, anyone can run a server, and people on different servers can still talk. Element is that protocol's most mature client, AGPL-3.0 licensed.
As an individual you can just use the public matrix.org server: sign up and go, with end-to-end encryption on by default for direct messages. For teams and organizations the real value is self-hosting — your own Synapse server, with the member list, message history and files all on your hardware, immune to a provider changing terms or raising prices. Several governments and universities run exactly this way.
Set expectations, though: it is more complex than a consumer messenger. Encryption keys must be backed up (without them, a new device cannot read old messages — do not skip this step); rooms, spaces and federation take a while to click; and the public server can be slow at peak times. Also note that end-to-end encryption protects message content, while metadata — which server you are on, who you talk to and when — is visible to the server. Self-hosting is the answer to that.
Who it suits: people who want team communication that is not locked to one vendor and who are willing to maintain a server. If you just want a secure private messenger with no admin work, look at Signal or SimpleX instead.