Generate TOTP

Generate a time-based one-time password from a Base32 secret.

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ToolTOTP Generator
Input
Output
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How it works

A Base32 secret and Unix time become a counter using a fixed time step; HMAC truncation then produces a six- or eight-digit code. The countdown shows how long the current time window remains.

  • RFC 6238 uses a 30-second step and commonly six digits.
  • SHA-1 remains the compatibility default for authenticator apps.

Worked example

The RFC 6238 SHA1 test secret at T=59
A fixed timestamp, since a real run would use the current time
Input
											Secret: GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ
Timestamp seconds: 59
Output
												Code: 287082
Seconds remaining: 1
Period start: 30
Period end: 60

When to use this

Authenticator apps, implementation test fixtures, and MFA enrollment run TOTP.

Edge cases

  • Unpadded but otherwise valid Base32 secrets still decode.
  • A clock several steps behind produces a different code.
  • One mistyped secret character produces a consistent but unusable code.

References