JWT Decoder

Parse JSON Web Tokens, inspect header parameters, claim payloads, and algorithm types instantly. Completely secure — never transmitted.

Encoded Token

Ready

Header (Algorithm & Type)

Header JSON

Payload (Claims Data)

Payload JSON

What is a JWT Token?

JSON Web Tokens (JWT) are a compact, URL-safe means of representing claims between two parties. They are widely used in authentication systems, API authorization, and single sign-on (SSO) implementations. A JWT token consists of three Base64URL-encoded parts separated by dots: the header, payload, and signature.

JWT Token Structure

Header: Contains the token type (JWT) and the hashing algorithm (e.g., HS256, RS256).
Payload: Contains the claims — statements about an entity (user) and additional metadata. Common claims include sub (subject), exp (expiration), iat (issued at).
Signature: Used to verify the token hasn't been altered. Created by signing the encoded header and payload with a secret key.

Our JWT decoder instantly decodes any valid JWT token, showing you the raw JSON header and payload with syntax highlighting, plus expiration status detection.