SignalUmbera
Phone number to sign upSignalRequired. Usernames let you start a chat without sharing your number, and the number is hidden by default from people who don’t have it saved.UmberaNot required. A username and password; no email either.
End-to-end encryption, one-to-one chatsSignalYes, by default. Built on the open-source Signal Protocol.UmberaYes, by default. Every chat; there is no unencrypted chat type.
End-to-end encryption, groupsSignalYes, by default. The service has no record of group memberships, titles or avatars.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 protectionSignalYes, for messages. PQXDH adds a post-quantum KEM to session setup against “harvest now, decrypt later”. SPQR (the Triple Ratchet), announced in October 2025, adds a post-quantum ratchet and is being rolled out gradually.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 metadataSignalSealed sender. Since 2018 the sender’s identity is sealed inside the encrypted envelope; the service sees the recipient’s delivery token.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 sourceSignalYes. The apps, libsignal and the server are published under AGPL-3.0.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 TorSignalNot documented. Signal documents support for TLS proxies to get past network blocks.UmberaYes. One switch routes all app traffic through Tor.
Channels and communitiesSignalNot documented. Signal has groups; we found no broadcast channels in its official sources.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 messagesSignalYes. A timer per conversation that applies to everyone in it.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.
PriceSignalFree. Run by a 501c3 nonprofit, no ads, supported by donations.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.