What is 2FA (two-factor authentication)?
Two-factor authentication adds a second proof of identity on top of your password. Learn the factor types and generate a TOTP second factor free.
Two-factor authentication (2FA) requires two independent proofs of identity to log in — typically your password plus a code from an app or device. Even if your password leaks, an attacker still cannot get in without the second factor.
The three factor types
Authentication factors come in three categories: something you know (a password or PIN), something you have (a phone, an authenticator app, a hardware key), and something you are (a fingerprint or face). 2FA combines two different categories — a password plus a phone code is 2FA; two passwords is not.
Common second factors
App-based TOTP codes are the sweet spot of security and convenience. SMS codes are easier but weaker (SIM-swap, interception). Push approvals and hardware security keys (FIDO2) are the strongest. Backup codes cover the case where you lose your device.
Why it matters
The vast majority of account takeovers start with a stolen or reused password. A second factor turns a leaked password from a full compromise into a non-event, which is why 2FA is the single highest-impact security step for any account.
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Use the TOTP generator in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.