OTP Generator Apps: How Authenticator Codes Work

An authenticator app, or OTP generator, makes a new 6-digit code every 30 seconds on your phone, with no text needed. Here is how it works.

How authenticator codes work

When you turn on app-based two-step sign-in, the service shows a QR code containing a secret key. Your authenticator app saves the key and combines it with the current time to make a code. The service does the same calculation, so both sides get the same code without any message being sent.

Why it beats text codes

• Works with no signal or when abroad.
• Cannot be redirected by a SIM swap.
• No waiting for a text that may not arrive.

Setting one up

1. Install a reputable authenticator app from your phone's app store.
2. In the account's security settings, choose two-step verification with an authenticator app.
3. Scan the QR code with the app.
4. Type the code the app shows to confirm.
5. Save the backup codes the service gives you, in a password manager or on paper.

Do not lose access

If your phone is lost, the codes go with it unless your app has backup or sync turned on. Keep the backup codes safe and read what to do if you lose your authenticator.

Choosing an authenticator

• Backup or sync: pick one that can back up your codes, so a lost phone does not lock you out.
• Export: an option to move codes to a new phone saves hours of re-setup.
• App lock: a PIN or fingerprint on the app stops someone with your unlocked phone reading codes.
• Well known: use an app from a recognised developer in the official app store.

FAQ

Is an OTP generator the same as an authenticator app?

Yes. Both make time-based codes on your device.

Why does my authenticator code not work?

Usually the phone clock is wrong. Turn on automatic date and time.

Can I use one authenticator for many accounts?

Yes. One app holds codes for as many accounts as you add.

Related: lost authenticator · passkeys · SMS vs app codes.