JWT Token Decoder

A JSON Web Token (JWT) is a compact, URL-safe token format used for securely transmitting information between parties as a JSON object. It consists of three parts: a Header (algorithm and token type), a Payload (claims/data), and a Signature. JWTs are widely used for authentication and authorization in web applications and APIs.

Yes, the header and payload of a JWT are only Base64URL-encoded, not encrypted. Anyone with the token can decode and read these parts. The secret key is only needed to verify the signature, which confirms the token has not been tampered with. This is why you should never store sensitive information in the JWT payload.

Session cookies store a session ID on the client, with the actual session data kept on the server. JWTs are self-contained tokens that carry all necessary data within the token itself. JWTs are stateless and work well in distributed systems and APIs, while session cookies require server-side storage. JWTs can be larger than session IDs but eliminate the need for server-side session lookups.