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JWT Decoder

Instantly decode JSON Web Tokens (JWT) to view header metadata and payload data.

Interactive Online Utility

JWT Decoder runs 100% locally in your browser sandbox with zero network roundtrips. Load or paste your code directly into the workspace above to format, parse, validate, or generate your output instantly. 

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SECURITY FACT JWTs are Signed, NOT Encrypted

A standard JWS (JSON Web Signature) only signs the header and payload with a cryptographic hash. Anyone with the token can decode and view claims by running atob(). Never put passwords, API tokens, or PII in JWT claims.

Technical Guide & Overview

JSON Web Tokens (JWT, RFC 7519) are compact, URL-safe URL claims containers used for stateless authentication and authorization in OAuth 2.0 and OpenID Connect protocols.

How It Works Under the Hood

A JWT comprises three base64url-encoded parts separated by periods: Header, Payload, and Signature. Otuls safely parses the header and payload segments, decoding claims (sub, exp, iat, aud, iss), formatting expiration timestamps into human-readable local time, and highlighting token validity status.

Authoritative Specifications & Primary Standards

Official specifications, RFCs, and authoritative open-source repositories for JWT Decoder:

IETF RFC

The internet standard defining compact URL-safe claims representation.

IETF RFC

Cryptographic signature format for verifying JWT authenticity and integrity.

GitHub Repository

Widely used open-source JavaScript library for parsing JWT headers and claims.

CLI Equivalents & Terminal Automation

Decode JWT payload using jq:
echo "$JWT" | cut -d. -f2 | base64 -d 2>/dev/null | jq .
Extracts and pretty-prints claims payload in bash.

Zero-Knowledge Client-Side Sandboxing

Your auth tokens, session bearer keys, and user claims are parsed entirely in your browser sandbox without ever hitting an authentication relay server.