JWT Decoder
No server upload
Paste your JWT token to instantly decode the Header and Payload. Automatically checks expiration time.
JWT Decoder
JWT Structure
Header
Payload
Expiration
Standard Claims
| Claim | Value | Description |
|---|
Signature
-
Guide
What is JWT?
JWT (JSON Web Token) is a compact token format used to transfer authentication and authorization data.
Header / Payload / Signature structure
Header contains algorithm metadata, Payload carries claims, and Signature protects against tampering.
Standard claims: exp, iat, sub
exp means expiration, iat is issued-at time, and sub identifies the token subject.
JWT vs session
JWT is stateless and self-contained, while session-based auth stores state on the server.
Why expiration check matters
Checking exp helps prevent using expired tokens and simplifies debugging authentication flows.