# Signal Private Messenger

A private messenger for Android.

Repository: https://github.com/signalapp/Signal-Android
Canonical: https://ross.abutalabs.com/products/signal-private-messenger
Homepage: https://signal.org
Language: Kotlin
License: AGPL-3.0
License Family: copyleft
Last push: 2026-08-26T20:11:44+00:00
Link (homepage): https://signal.org
Link (site_page): https://signal.org/docs

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 86, longevity 100
- inputs: {"age_days": 5375, "days_push": 7, "days_rel": 12, "gap_med": 3, "n_releases_24m": 152}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 29262, forks 6857 (observed 2026-08-28T04:11:53.230204+00:00)

## What it is
Signal is a free, open-source private messenger offering end-to-end encrypted text, voice, and video communication, built on the Signal Protocol (including post-quantum PQXDH and Double Ratchet). It spans Android, iOS, and Desktop clients with a companion server and libsignal cryptographic libraries.

## Use cases
- send encrypted messages to friends
- make private voice and video calls
- replace whatsapp with a privacy-focused messenger
- chat securely without ads or trackers
- self-host or study an e2e-encrypted messaging protocol
- integrate the signal protocol into another app via libsignal

## When to choose
- you need strong, always-on end-to-end encryption for messaging and calls
- you want a free, ad-free messenger backed by a nonprofit
- you need cross-platform clients (Android, iOS, Desktop)
- you want to study or reuse a battle-tested cryptographic protocol

## When to avoid
- you need a self-hostable server for a small team - Signal's server is designed for its own network
- you require anonymous registration without a phone number
- you need heavy enterprise features like admin compliance tooling or directory integration

## Facets
- artifact type: application
- maturity: stable
- function: chat-interface, cryptography, security, video-processing, audio-processing
- domain: privacy, messaging-platforms, security, cross-platform
- platform: cross-platform, self-hosted
- tags: end-to-end-encryption, signal-protocol, messenger, voice-calls, video-calls, post-quantum-cryptography, nonprofit, android, ios, desktop

## Member repositories
- signalapp/Signal-Android (main) score 95
- signalapp/Signal-Desktop (main) score 95
- signalapp/Signal-iOS (main) score 95
- signalapp/Signal-Server (backend) score 77
- signalapp/libsignal (sdk) score 95
- signalapp/libsignal-protocol-javascript (sdk) score 10
- signalapp/libsignal-protocol-java (sdk) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:53.230204+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T16:53:04.142178+00:00, confidence not recorded.
  - readme: https://github.com/signalapp/Signal-Android (fetched 2026-08-28T04:11:53.230204+00:00, sha cc3e6a5d159e)
  - homepage: https://signal.org (fetched 2026-08-29T07:50:55.510955+00:00, sha 0ad4ae87f44d)
  - site_page: https://signal.org/docs (fetched 2026-08-29T07:50:55.519939+00:00, sha c83439b6489d)
- Data as of 2026-08-30T08:39:29.467469+00:00.