About OTP Generator
Use OTP Generator to Debug TOTP/2FA. The tool runs in your browser for fast results and keeps your data local.
How to Use
- 1. Add your input or data.
- 2. Adjust options if needed.
- 3. Review the result and copy it.
What is TOTP?
TOTP (Time-based One-Time Password) is a two-factor authentication algorithm that generates temporary codes based on the current time and a shared secret key. TOTP codes are typically 6 digits, change every 30 seconds, and are used by apps like Google Authenticator, Authy, and Microsoft Authenticator. The algorithm (RFC 6238) combines the secret key with the current Unix timestamp divided by 30, then applies HMAC-SHA1 hashing. TOTP provides strong security for account protection, requiring both something you know (password) and something you have (device with TOTP app). Understanding TOTP is essential for implementing multi-factor authentication and debugging MFA issues.
Common Use Cases
TOTP is essential for multi-factor authentication and security. Developers implement TOTP for user account protection in web applications. Security teams test MFA implementations and troubleshoot authentication issues. System administrators set up TOTP for server and VPN access. Users recover access when authenticator apps are lost or reset. Developers debug TOTP integration with third-party services. Penetration testers verify TOTP implementation security. Backup and recovery teams generate emergency access codes.
- Implementing MFA for user accounts
- Testing and debugging TOTP implementations
- Server and VPN access authentication
- Account recovery when authenticator lost
- Debugging third-party TOTP integrations
- Security testing of MFA systems
- Emergency access code generation
- Migrating TOTP secrets between devices
Best Practices & Tips
Store TOTP secrets securely—they provide full account access if compromised. Use Base32 encoding for secrets as per RFC standard. Implement time synchronization tolerance (±1 period) for clock skew. Provide backup codes for account recovery if TOTP device is lost. Use QR codes for easy secret transfer to authenticator apps. Implement rate limiting to prevent brute force attacks on TOTP codes. Allow users to disable TOTP only after verifying identity. Test TOTP implementation with multiple authenticator apps for compatibility.
- Store secrets securely—they grant full access
- Use Base32 encoding per RFC standard
- Implement ±1 period tolerance for clock skew
- Provide backup codes for device loss
- Use QR codes for easy secret transfer
- Rate limit to prevent brute force attacks
- Require identity verification to disable TOTP
- Test with multiple authenticator apps
Troubleshooting Common Issues
If TOTP codes do not work, verify device time is synchronized—clock skew causes mismatches. If codes are rejected, check the secret is correctly encoded in Base32. If QR code scanning fails, manually enter the secret key. If codes work intermittently, implement time tolerance (±30 seconds). If multiple devices show different codes, verify they use the same secret. If codes never work, verify the TOTP algorithm matches (SHA1 is standard). If backup codes fail, verify they are single-use and not expired. If time sync is impossible, use HOTP (counter-based) instead of TOTP.
- Clock skew causing code mismatches
- Incorrect Base32 encoding of secret
- QR code scanning failures
- Intermittent failures from time tolerance issues
- Different codes on multiple devices
- Algorithm mismatch (SHA1 vs SHA256)
- Backup codes already used or expired
- Time synchronization impossible on device
Frequently Asked Questions
Is OTP Generator free to use?
Yes. OTP Generator is free and works directly in your browser.
Does OTP Generator upload my data?
No. Most processing happens locally. Any network requests are clearly indicated.
What formats does OTP Generator support?
OTP Generator supports the common formats described on the page. Convert uncommon formats before pasting.
How should I share results from OTP Generator?
Copy the output and review any sensitive data before sharing or publishing.