Background: Messaging explains end-to-end encryption and the settings that matter; Communication Metadata explains why "encrypted" is only half the question.
Signal: default recommendation
What it is: an open-source, end-to-end-encrypted messenger run by a nonprofit, whose protocol is the industry reference implementation.
Who it's for: everyone, for everything, the point of a messenger is the people on it, and Signal is the strong option with mainstream reach.
Why: E2EE always on for messages, calls, and groups with no unencrypted mode to mis-select; metadata retention demonstrated to be near-zero by its published responses to actual subpoenas;[1] sealed sender and private contact discovery reduce what the server can learn structurally; usernames now allow hiding your phone number from contacts; disappearing messages, safety-number verification, encrypted local backups.
Drawbacks: registration still requires a phone number (visible to Signal, though hideable from contacts), a real limitation for compartmentalized identities; centralized infrastructure, so availability depends on one organization; no federation.
Licensing: open source (AGPL clients/server); funded by the Signal Foundation.
SimpleX Chat: when metadata is the threat
What it is: an open-source messenger with no user identifiers at the protocol level, no phone number, no username, not even a persistent ID connecting your conversations to each other.
Who it's for: contacts between compartmentalized identities; people for whom the contact graph (who talks to whom) is itself the sensitive datum.
Why: the strongest metadata design in usable messaging: message queues are unidirectional and per-contact, so the servers can't assemble a graph; self-hostable relays; audited.[2]
Drawbacks: small network, you'll be inviting people, not finding them; multi-device support and polish behind Signal; newer cryptographic and operational track record; usability tradeoffs that are the direct price of the metadata properties.
Licensing: open source (AGPL).
The ones people already use
WhatsApp. Content is genuinely E2EE (Signal protocol) and that matters; Meta's collection of the contact graph, group memberships, and behavioral metadata is the price. If it's where your family is: turn on encrypted backups, and treat it as content-private, metadata-shared, better than SMS, not a Signal substitute.
iMessage. Solid E2EE between Apple devices if backups are handled: without Advanced Data Protection, iCloud Backup gives Apple the keys to your history. Falls back silently to carrier SMS/RCS with green-bubble contacts.
Telegram. not recommended as a private messenger. Default chats and all groups are server-readable; E2EE requires manually starting a "Secret Chat," which nobody does; the operator holds message content at scale, whatever its moderation posture in any given year. Fine as a social platform; wrong tool for confidentiality.
Not recommended
Carrier SMS/MMS for anything sensitive (no encryption, full carrier records), and boutique "military-grade encrypted" apps without published protocols, audits, or a reason to exist, the graveyard of seized "secure phone" companies (EncroChat, Sky ECC, and the FBI-run ANOM) is a reminder that unverifiable privacy claims are worse than none.
Signal, Government Requests. ↩︎
SimpleX, security assessment by Trail of Bits (2022), with subsequent audits linked from the same blog. ↩︎