JWT Decoder
Decode and analyze JSON Web Tokens (JWT)
security JWT Decoder
help_outline Understanding JWT
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.
JWT Structure
- looks_one Header: Contains token type and signing algorithm
- looks_two Payload: Contains claims (user data and metadata)
- looks_3 Signature: Verifies token integrity and authenticity
Common Claims
iss (Issuer)
Token issuer identifier
sub (Subject)
Subject/user identifier
exp (Expiration)
Token expiration timestamp
iat (Issued At)
Token creation timestamp
Important:
JWT payload data is encoded, not encrypted. Anyone with the token can read its contents. Never include sensitive information in JWT claims.
code Example JWT Token
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
Header:
{"alg":"HS256","typ":"JWT"}
Payload:
{"sub":"1234567890","name":"John Doe","iat":1516239022}
Signature:
HMACSHA256(base64UrlEncode(header) + "." + base64UrlEncode(payload), secret)