JWT Decoder

Decode and inspect JSON Web Tokens instantly. View header, payload, and signature with syntax highlighting.

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Instant Decoding

Decode JWT tokens instantly with one click.

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Clear Display

Beautiful JSON formatting with syntax highlighting.

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100% Private

All decoding happens in your browser. No server requests.

Understanding JSON Web Tokens (JWT)

JSON Web Tokens (JWT) are a compact, URL-safe means of representing claims to be transferred between two parties. They are commonly used for authentication and information exchange in modern web applications. A JWT consists of three parts separated by dots: Header, Payload, and Signature.

JWT Structure

  • Header: Contains the token type (JWT) and signing algorithm (e.g., HS256, RS256)
  • Payload: Contains the claims - statements about an entity and additional data
  • Signature: Used to verify the token hasn't been tampered with

Common Use Cases

JWTs are widely used for authorization (allowing users to access routes and resources), information exchange (securely transmitting information between parties), and stateless authentication (maintaining user sessions without server-side storage). They're particularly popular in RESTful APIs and microservices architectures.

Security Considerations

While JWTs are signed to prevent tampering, the payload is only Base64 encoded, not encrypted. Never store sensitive information like passwords in JWT payloads. Always use HTTPS for transmission, implement proper expiration times, and validate tokens on the server side.

FAQ

What is a JWT token?â–¼

JWT (JSON Web Token) is a compact, self-contained way to securely transmit information between parties as a JSON object.

Is JWT decoding secure?â–¼

Yes! All decoding happens in your browser. Your JWT tokens never leave your device or get sent to any server.

Can I verify JWT signatures?â–¼

This tool decodes JWT structure. Signature verification requires the secret key and should be done server-side.

What are JWT claims?â–¼

Claims are statements about an entity (typically the user) and additional metadata. Common claims include sub (subject), iat (issued at), exp (expiration).

Why use JWT for authentication?â–¼

JWTs are self-contained, stateless, and can be easily passed between services. They reduce database lookups and work well in distributed systems.