What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used to securely transmit information between parties. JWTs consist of three parts: a header specifying the algorithm, a payload containing claims, and a signature for verification.
How JWT Signing Works
This tool uses HMAC-SHA256 (HS256) to sign tokens. The header and payload are Base64URL-encoded, concatenated with a period, then signed with your secret key using the Web Crypto API. The resulting signature ensures the token has not been tampered with.
Common JWT Use Cases
JWTs are widely used for authentication (login tokens), authorization (API access), and information exchange (secure data transfer between services). They are stateless, meaning the server does not need to store session data.