Signal vs WhatsApp Comparison

Double Ratchet with PQXDH, a post-quantum key agreement (September 2023); a Sparse Post-Quantum Ratchet added on top was announced in October 2025

The Signal Protocol, with Sender Keys for group chats; connections between the apps and WhatsApp's servers run through a separate Noise-based encrypted channel.

Sealed sender hides who is sending a message from Signal's servers, which still see the recipient and the connection's IP address. A phone number is still needed to sign up; usernames only hide it from other users.

WhatsApp collects usage, device and connection information and shares information with the other Meta companies; it states it does not retain messages once they are delivered.

Operated by Signal Messenger LLC; the trademarks belong to Signal Technology Foundation, a 501(c)(3) nonprofit.

WhatsApp LLC is based in Menlo Park, California; users in the EEA are served by WhatsApp Ireland Limited.

Implementation review of the Auditable Key Directory library behind WhatsApp's key transparency feature, commissioned by Meta; a separate 2024 NCC Group assessment covered the protocol that stores contacts. Neither covers the apps' messaging code as a whole.

Grants and donations, plus an initial loan from Brian Acton. Signal's own November 2023 estimate puts running costs at about $50 million a year by 2025.

Funded by its parent company, Meta. Ads appear only in Status and Channels, separate from personal chats and calls.