SessionUmbera
Phone number to sign upSessionNot required. No phone number or email.UmberaNot required. A username and password; no email either.
End-to-end encryption, one-to-one chatsSessionYes, by default.UmberaYes, by default. Every chat; there is no unencrypted chat type.
End-to-end encryption, groupsSessionYes, by default. Groups of up to 100 members.UmberaYes, by default. Groups use MLS (RFC 9420). The server doesn’t know a message is for a group or who is in it.
Post-quantum protectionSessionNot yet. Session Protocol V2, in development, is planned to add post-quantum cryptography and restore perfect forward secrecy.UmberaMessages: yes. Calls: no. Every message envelope is sealed with X25519 and ML-KEM-1024 together. Calls use DTLS-SRTP (WebRTC), which is not post-quantum.
Sender and metadataSessionOnion routing. Messages travel through the Session network as onion requests. Calls are peer-to-peer, so the IP address is visible to the other person and to a STUN/TURN server.UmberaSender sealed inside the ciphertext. Messages go to a mailbox address only the two people can derive, and it changes periodically. Sizes are padded to blocks. The server sees the delivery time.
Open sourceSessionYes. The apps are published under GPL-3.0, the storage server under MIT.UmberaCryptographic core only. umbera-core (Rust) is open source under Apache-2.0 on GitHub and crates.io. The app and the server code are not published.
Built-in TorSessionNo, its own network. Session describes its onion routing as similar to Tor, with some differences.UmberaYes. One switch routes all app traffic through Tor.
Channels and communitiesSessionYes, Communities. Large public, self-hosted groups; messages are encrypted only in transit to the community server.UmberaYes, Communities. Channels with a separate pseudonym in every channel; private channels are end-to-end encrypted. Open during the trial, then part of Umbera Premium.
Disappearing messagesSessionYes. “Disappear after send” or “Disappear after read”; removed from both devices and from the network.UmberaIn one-to-one chats. 1 minute, 1 hour, 1 day or 1 week; deleted on both phones, attached files deleted from the server. Not available in groups yet.
PriceSessionFree. Session says it will always remain free to use; “Session Pro” premium features may come later.UmberaFree plan and a subscription. After a free trial, a few contacts stay free for good. Encryption, Tor and Shield are always free. Umbera Premium adds any number of people, groups and Communities.