JWT Inspector

JWT Inspector decodes the header and payload segments of a JSON Web Token so a researcher can review visible claims without sending the token to a remote service. It is useful for checking claim names, expiration timestamps, issuer/audience values, algorithm declarations, and obvious formatting mistakes.

The tool does not verify signatures, generate tokens, brute-force secrets, test algorithms, contact issuers, or validate authorization decisions. It is intentionally read-only and structural. Do not paste sensitive production tokens unless the local browser environment is already approved for that material.

Local Processing Boundary

This tool runs in the browser. It does not upload input, call a backend API, or store values unless the page explicitly says otherwise.

This viewer decodes JWT header and payload segments only. It does not verify signatures, generate tokens, crack secrets, or make network calls.

JWT

Data Handling

• Token text remains in the browser tab.
• No network request is made by this component.
• No token is stored in local storage, session storage, IndexedDB, cookies, or a backend system.
• Decoded output is generated only for the current page session.

Data handling is part of the tool boundary. The page should say whether input stays in the browser, whether anything is stored, whether network calls are made, and what the output can and cannot prove.

Boundary

Decoded JWT content is not proof that a token is valid. A token can decode cleanly while being expired, forged, unsigned, signed by the wrong key, scoped for another audience, or unusable by the relying party. Use this tool only for structural review and copy-safe reporting, not authentication decisions.