Is my 2FA secret key stored or uploaded to any server?

No. Your secret key is processed strictly in your local device RAM using client-side JavaScript. When you close or refresh the browser tab, the key is permanently purged from memory.

Why does my generated 2FA token not match my authenticator app?

TOTP codes depend on synchronized system time. Ensure your computer or smartphone device clock is set to automatic network time synchronization (NTP), as time discrepancies greater than 30 seconds will cause code mismatches.

What character formats are accepted for secret keys?

Standard two-factor setup keys use Base32 encoding containing uppercase letters A–Z and digits 2–7. Spaces and hyphens are automatically stripped out during processing.

Can this tool replace a mobile authenticator app?

This tool is designed for testing, recovery, and desktop developer workflows. For daily mobile security, we recommend storing two-factor credentials in a dedicated hardware token or encrypted authenticator app.

Security & Auth

2FA / TOTP Authenticator Code Generator

Generate 6-digit Time-based One-Time Passwords (RFC 6238) from your secret keys locally in your browser with real-time countdown.

🔒 100% Private In-Browser TOTP: HMAC calculations run natively in your browser using the Web Crypto API. Secret keys are never transmitted or stored.

Current 2FA Auth Code30s remaining

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Active One-Time Password

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Valid for the next 30 seconds (RFC 6238 SHA-1 6-digit OTP)

2FA Base32 Secret Key

Paste the Base32 setup key provided by Google Authenticator, GitHub, Amazon, or your auth provider.

Digits

Time Step Period

HMAC Algorithm

100% Private. Your data never leaves your device.

FreeToolsBox • Instant & Free

What is 2FA / TOTP Authenticator Code Generator?

The 2FA / TOTP Authenticator Generator computes standard 6-digit Time-based One-Time Password (TOTP) authentication codes from your Base32 secret key. Compatible with Google Authenticator, Authy, Microsoft Authenticator, and 1Password, it executes RFC 6238 cryptographic HMAC calculations directly in your browser with zero data storage.

Designed for accuracy, speed, and privacy, this tool runs entirely on your local device with zero network latency.

How to Use the 2FA / TOTP Authenticator Code Generator

1
Enter your Base32 Secret Key (the alphanumeric setup key provided by your service during 2FA configuration).
2
Optionally customize token parameters (standard default: 6 digits, 30-second time step, HMAC-SHA-1 algorithm).
3
Watch the live 6-digit authentication token generate in real time alongside a synchronized countdown progress ring.
4
Click the token to copy it instantly and paste into your two-factor login verification screen.

Formula & Calculation Logic

Implements the IETF RFC 6238 TOTP standard and RFC 4226 HOTP dynamic truncation algorithm to convert 30-second Unix time intervals and cryptographic shared secret keys into synchronized 6-digit tokens.

T = floor((Current_Epoch_Time - T0) / Time_Step) | TOTP = Truncate(HMAC-SHA-1(Secret, T)) mod 10^Digits

2FA / TOTP Authenticator Code Generator Frequently Asked Questions

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