JWT Decoder

What Is a JWT Decoder?

A JWT (JSON Web Token) decoder is a tool that parses and inspects the contents of a JSON Web Token without validating its signature. JWTs are widely used for authentication and authorization in modern web applications and APIs. A typical JWT consists of three parts: a header that specifies the token type and signing algorithm, a payload that contains claims about the user and session, and a signature that verifies the token integrity.

Our JWT Decoder instantly decodes any valid JWT and displays the header and payload in a readable JSON format, along with the raw signature. This is useful for debugging authentication flows, inspecting token expiration times, verifying user claims, and understanding what data your application is sending and receiving in tokens.

How to Use the JWT Decoder

Paste your JWT string into the input field above. The token should be a complete JWT with three dot-separated segments (header.payload.signature). Click "Decode" and the tool immediately parses the token, displaying the decoded header and payload as formatted JSON. The signature is shown as a raw string since it cannot be decoded without the secret key.

Note that this tool only decodes the token - it does not verify the signature. To verify a JWT, you need the original signing secret or public key. The decoded payload will show standard claims such as "iss" (issuer), "sub" (subject), "exp" (expiration time), "iat" (issued at), and any custom claims your application includes. Use this information to debug authentication issues, check token expiration, or audit the claims your application is using.