What is a JSON Web Token (JWT)?
A JSON Web Token (JWT) is a compact, URL-safe token format used for securely transmitting information between parties. JWTs are commonly used for authentication and authorization in web applications and APIs.
JWT Structure
A JWT consists of three parts separated by dots: the Header (algorithm and token type), the Payload (claims and data), and the Signature (verification). Each part is Base64Url encoded.
Why Decode JWTs Client-Side?
JWTs often contain sensitive information like user IDs, roles, and permissions. Sending them to a third-party server for decoding poses a significant security risk. Our decoder processes everything in your browser — the token never leaves your device.