TOTP Code Generator
Generate the six-digit authenticator code for a TOTP secret, read an otpauth:// QR link, and check that your server and your app agree.
Spaces and lower case are fine.
Files are processed in your browser and are never uploaded to a server.
How to use
Free to use with no sign-up, no install and no usage limit.
Paste a base32 secret and the current code appears, refreshing on its own as each period ends. This is the same calculation an authenticator app does, so if the code here matches the one your app shows, the secret was copied correctly.
It is most useful when something does not line up. If your server rejects a code that the app shows, generate the code here: matching here but rejected there points at the server clock, while a different code here points at the secret itself.
You can also paste a whole otpauth:// link from a setup QR code. The issuer, account, algorithm, digit count and period are all read out of it, so you can see exactly what the service asked for instead of guessing.
The secret is never sent anywhere. The code is computed in your browser with the built-in Web Crypto HMAC, and nothing is stored after you close the page.
Because it is not stored, this is a checking tool rather than a replacement for an authenticator app. Treat a TOTP secret like a password: anyone holding it can produce valid codes forever, so do not paste one into a shared screen.
The generator follows RFC 6238 and is checked against that document’s own published test values, including the SHA-256 and SHA-512 variants some services use.