Google Authenticator is a software-based
authenticator
An authenticator is a means used to confirm a user's identity, that is, to perform digital authentication. A person authenticates to a computer system or application by demonstrating that he or she has possession and control of an authenticator. I ...
by
Google
Google LLC () is an American multinational technology company focusing on search engine technology, online advertising, cloud computing, computer software, quantum computing, e-commerce, artificial intelligence, and consumer electronics. ...
that implements
two-step verification
Multi-factor authentication (MFA; encompassing two-factor authentication, or 2FA, along with similar terms) is an electronic authentication method in which a user is granted access to a website or application only after successfully presenting ...
services using the
Time-based One-time Password Algorithm
Time-based one-time password (TOTP) is a computer algorithm that generates a one-time password (OTP) that uses the current time as a source of uniqueness. As an extension of the HMAC-based one-time password algorithm (HOTP), it has been adopted a ...
(TOTP; specified in RFC 6238) and
HMAC-based One-time Password algorithm
HMAC-based one-time password (HOTP) is a one-time password (OTP) algorithm based on HMAC. It is a cornerstone of the Initiative for Open Authentication (OATH).
HOTP was published as an informational IETF RFC 4226 in December 2005, documenting th ...
(HOTP; specified in RFC 4226), for authenticating users of software applications.
When logging into a site supporting Authenticator (including Google services) or using Authenticator-supporting third-party applications such as
password manager
A password manager is a computer program that allows users to store and manage their passwords for local applications and online services. In many cases software used to manage passwords allow also generate strong passwords and fill forms. Pas ...
s or
file hosting service
A file-hosting service, cloud-storage service, online file-storage provider, or cyberlocker is an internet hosting service specifically designed to host user files. It allows users to upload files that could be accessed over the internet afte ...
s, Authenticator generates a six- to eight-digit
one-time password
A one-time password (OTP), also known as a one-time PIN, one-time authorization code (OTAC) or dynamic password, is a password that is valid for only one login session or transaction, on a computer system or other digital device. OTPs avoid seve ...
which users must enter in addition to their usual login details.
Google provides
Android,
BlackBerry
The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus''. The taxonomy of ...
, and
iOS
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also includes ...
versions of Authenticator.
An official open-source fork of the Android app is available on GitHub.
However, this fork has not been updated since 2020. Likewise, for old versions of the Google Authenticator apps for iOS and BlackBerry, the source code is also freely available. Yet this source code, too, has not been updated in years.
Current releases of the software are