TOTP / 2FA Authenticator Simulator

Generate time-based one-time password (TOTP) 2FA verification codes from secrets or QR codes
This free online totp / 2fa authenticator simulator runs in your browser and is part of our Cryptography collection.

TOTP / 2FA Authenticator Simulator

Generate and test RFC 6238 Time-based One-Time Password (TOTP) codes for two-factor authentication from Base32 secret keys.

Current 2FA One-Time Passcode
- - - - - -
Refreshing in: 30s

Secret Key Configuration

Standard format provided by GitHub, Google, AWS, and Cloudflare.

Verify Code / Clock Window

Previous Window (-30s): -
Next Window (+30s): -

How RFC 6238 TOTP Works

  • Time-step counter: T = floor(current_unix_time / 30).
  • HMAC calculation: Computes HMAC-SHA1(Secret, T).
  • Dynamic Truncation: Extracts an offset index from the last nibble of the hash to extract a 31-bit integer, then formats modulo 10^digits.
  • Compatible with Google Authenticator, Authy, 1Password, and Bitwarden.

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