Header (ALGORITHM & TOKEN TYPE)
Payload (DATA)
Signature
About JWT Decoder
This tool decodes JSON Web Tokens (JWT) and displays the header, payload, and signature. All processing happens in your browser - no data is sent to any server.
Instant Decode
Decode JWT header and payload in real-time.
Expiration Check
Automatically check if the token has expired.
Secure
100% client-side. Your tokens never leave your browser.
Share
Generate shareable URLs for quick debugging.
What is a JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. JWTs are commonly used for:
- Authorization: Once a user logs in, subsequent requests include the JWT
- Information Exchange: Securely transmit data between parties
- Single Sign-On (SSO): Share authentication across multiple systems
JWT Structure
A JWT consists of three parts separated by dots:
- Header: Token type and signing algorithm
- Payload: Claims (user data, metadata)
- Signature: Verification that the token is authentic
Common JWT Claims
- iss - Issuer
- sub - Subject
- aud - Audience
- exp - Expiration Time
- nbf - Not Before
- iat - Issued At
- jti - JWT ID