Google Authenticator

Google Authenticator is a free mobile app from Google that generates short, time-limited codes used for two-factor authentication. When a user sets it up for an account, such as a crypto exchange, the service shows a QR code containing a shared secret. The app then combines that secret with the current time to produce a new six-digit one-time password every 30 seconds, following an open standard known as TOTP. Because the code is created on the phone, it works offline and is much harder to intercept than a code sent by text message, which can be stolen through SIM swapping. Users should keep backup codes, since losing the phone can lock them out; Google added optional cloud backup in 2023. The app does not protect against all phishing, as a code typed into a fake site can still be used quickly by an attacker.