JWT Decoder & Debugger - Inspect & Parse JSON Web Tokens Online

About this Utility

The JWT Decoder & Debugger is a secure diagnostic utility designed to instantly decode and inspect JSON Web Tokens (JWT). JWTs are the industry standard for securing stateless authentication, single sign-on (SSO) systems, and modern API gateways.

A standard JWT consists of three parts separated by dots: Header, Payload, and Signature. Our real-time decoder splits these tokens, decodes the base64url strings, and renders the JSON payloads with elegant syntax highlighting. This allows you to verify token expiration, check scopes, audit issuer metadata, and debug login flows safely without risking credential leaks.

How to Use Step-by-Step

  1. Paste token string: Copy your raw JSON Web Token (usually beginning with "eyJ") and paste it into the editor.
  2. Split and decode: The engine instantly parses the token, isolating the Header, Payload, and Signature segments.
  3. Audit claim metadata: Inspect key JWT claims like issuer (iss), subject (sub), expiration (exp), and roles in real-time.
  4. Confirm expiration state: Review the visual expiration countdown indicator to verify if the token is still valid.

Frequently Asked Questions

🔒 Is it safe to paste my production access tokens here?

Yes! Unlike online utilities that send pasted keys to their servers, our JWT Decoder operates 100% offline in your browser window. Your private authentication tokens never leave your local session.

🔍 What are the three parts of a JSON Web Token?

They are: 1) The Header (specifying the token type and cryptographic algorithm), 2) The Payload (containing claims, user details, and permissions), and 3) The Signature (used to verify that the sender is who they say they are and that the token was not modified).

⏳ How does the tool determine if a JWT has expired?

The decoder extracts the "exp" (expiration time) claim from the payload, which is formatted as a Unix timestamp. It then compares this timestamp to your system's current time, instantly indicating whether the token remains active.