# Google Authenticator

Open source fork of the Google Authenticator Android app

Repository: https://github.com/google/google-authenticator-android
Canonical: https://ross.abutalabs.com/products/google-authenticator
Homepage: https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2
Language: Java
License: Apache-2.0
License Family: permissive
Archived: true
Last push: 2020-06-09T13:34:39+00:00
Link (homepage): https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4347, "days_push": 2276, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1670, forks 483 (observed 2026-08-28T04:05:20.071974+00:00)

## What it is
The open-source implementations of Google Authenticator, generating one-time passcodes using the OATH HOTP (RFC 4226) and TOTP (RFC 6238) standards. It includes mobile apps for iOS and Blackberry, an Android app, and a PAM module for Linux two-factor authentication.

## Use cases
- generate two-factor authentication codes on my phone
- add TOTP 2FA to Linux SSH login
- implement RFC 6238 time-based one-time passwords
- self-hosted two-factor authentication without account backups
- verify user identity with one-time passcodes

## When to choose
- you need standards-compliant HOTP/TOTP code generation
- you want 2FA on Linux logins via PAM
- you prefer no cloud account backups for security reasons

## When to avoid
- you want the current Play Store/App Store Google Authenticator app with cloud sync
- you need actively developed mobile apps - the code has diverged from store versions
- you need push-based or modern 2FA methods beyond OTP

## Facets
- artifact type: application
- maturity: maintenance
- function: auth, security, cryptography
- domain: security, privacy, mobile-development
- platform: cross-platform
- tags: totp, hotp, two-factor-authentication, otp, pam, open-authentication, ios, android, linux

## Member repositories
- google/google-authenticator-android (main) score 10
- google/google-authenticator (main) score 10
- google/google-authenticator-libpam (plugin) score 63

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:20.071974+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 2026-08-29T17:58:47.574172+00:00, confidence not recorded.
  - readme: https://github.com/google/google-authenticator-android (fetched 2026-08-28T04:05:20.071974+00:00, sha 53556023dd12)
  - homepage: https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2 (fetched 2026-08-29T08:53:04.077853+00:00, sha 44136fa355b3)
- Data as of 2026-08-30T08:39:29.467469+00:00.