Instant Decoding
Decode JWT tokens with a single click. See header, payload, and signature immediately.
JWT Decoder
Decode and validate JSON Web Tokens (JWT) instantly. View header, payload, and signature. Perfect for debugging API authentication.
HEADER
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PAYLOAD
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SIGNATURE
Why Use Our JWT Decoder?
Claim Analysis
View all standard JWT claims including exp, iat, sub, and more with human-readable timestamps.
Expiry Check
Automatically check if the token is expired or valid based on exp claim.
100% Client-Side
All decoding happens in your browser. Your tokens are never sent to any server.
What is JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.
JWT Structure
A JWT consists of three parts separated by dots:
- Header: Contains the token type (JWT) and signing algorithm (HS256, RS256, etc.)
- Payload: Contains the claims - statements about the user and additional data
- Signature: Used to verify the token hasn't been tampered with
Common JWT Claims
- iss (Issuer): Who issued the token
- sub (Subject): Who the token represents
- aud (Audience): Intended recipient
- exp (Expiration Time): When token expires
- iat (Issued At): When token was created
- jti (JWT ID): Unique identifier for the token
JWT in API Authentication
JWTs are commonly used in modern authentication systems like OAuth 2.0 and OpenID Connect. When a user logs in, the server issues a JWT that the client includes in subsequent API requests. The server validates the token signature to authenticate the user without storing session data.