Question 1

What does the JWT signer do?

Accepted Answer

It creates a signed JSON Web Token from the header and payload you provide, using an HMAC secret (HS256, HS384 or HS512). It is handy for testing APIs and authentication flows.

Question 2

Is my secret sent anywhere?

Accepted Answer

No. Signing happens in your browser with the Web Crypto API, so your secret and payload never leave your device.

Question 3

Can it verify or decode tokens?

Accepted Answer

This tool focuses on signing. To decode and inspect an existing token, use the separate JWT decoder tool.

JWT Signer