Our verdict: Signal is the benchmark for private messaging — end-to-end encrypted by default, fully open source, and run by a nonprofit with no ads or trackers.
Signal is a free, end-to-end encrypted messenger for one-to-one chats, groups, voice and video calls, and file sharing. Every conversation is protected by the open-source Signal Protocol — the same cryptography later adopted by much of the industry — and encryption is always on, never an opt-in setting. The service is operated by Signal Messenger, LLC under the Signal Technology Foundation, a 501(c)(3) nonprofit that is deliberately independent of any major technology company and funded by donations rather than data.
The apps for Android, iOS, Windows, macOS, and Linux are published under the AGPL-3.0 license with the full source code on GitHub, and Signal's promise of 'No ads. No trackers.' is borne out by independent analysis: the latest Exodus Privacy scan of the Android app found zero tracker signatures. With formally analyzed cryptography — including the post-quantum PQXDH key agreement introduced in 2023 — and a steady release cadence across all platforms, Signal remains the default recommendation for anyone who wants mainstream messaging convenience without surveillance.
