End-to-end encryption has long been the standard — WhatsApp, Signal, Threema and VOID all advertise it. But "encrypted" doesn't automatically mean "private." What matters is which metadata is generated, whether a phone number is required and who runs the servers. Here is an honest comparison.
What really matters
The content of your messages is end-to-end encrypted on all four messengers. The differences lie elsewhere:
- Phone number: a unique identity anchor that ties your account to your real-world identity.
- Metadata: who talks to whom, when and how often — highly sensitive even without the content.
- Server operation: who owns the servers, which country they sit in, and what gets logged?
Uses the well-regarded Signal protocol for message content — technically solid. The problem is everything around it: WhatsApp is owned by Meta, requires a phone number and collects extensive metadata (contacts, usage patterns, device info). Depending on your settings, cloud backups are not end-to-end protected.
Signal
The gold standard for encryption, open source and non-profit. Signal actively minimizes metadata (for example with "Sealed Sender"). Two limitations remain: a phone number is still required, and the infrastructure is centralized (mostly in the USA).
Threema
From Switzerland, with no phone number requirement and with sparing metadata — a strong privacy approach. However, the servers are likewise run centrally by the provider, and the app costs money.
VOID
VOID relies on the open Matrix protocol (end-to-end with Olm for one-on-one and Megolm for group chats). The difference lies in the trust model:
- No phone number — access runs through an activation code, not your phone number.
- Only its own no-logging server — there is no federation with third-party Matrix servers, so no data flows to third parties.
- Messages, media and keys stay end-to-end encrypted and exclusively on your device.
The comparison at a glance
| Messenger | E2E content | No phone number | Server operation | Metadata |
|---|---|---|---|---|
| Yes | No | Meta (USA) | Extensive | |
| Signal | Yes | No | Centralized (USA) | Minimized |
| Threema | Yes | Yes | Centralized (CH) | Low |
| VOID | Yes | Yes | Own no-logging server | No logs |
Conclusion
Signal remains an excellent choice for the broad public. But anyone who wants to avoid the phone number as an identity anchor and trust their own, log-free server instead of a central platform is better served by VOID. VOID comes preinstalled on every SaferPhone.