JWT Decoder
Decode and inspect the header, payload, and expiry of any JWT token.
How it works
Paste any JWT (JSON Web Token) string into the decoder. It instantly splits the token into header, payload, and signature sections, decodes the Base64 content, and displays the claims — including expiry (exp), issued-at (iat), and subject (sub).
Why use this tool?
Developers debugging authentication issues use this free JWT decoder to inspect token contents without needing jwt.io. Works fully offline — your token never leaves your browser.
Frequently Asked Questions
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication. It contains three base64-encoded sections: header (algorithm type), payload (claims/data), and signature (verification).
Can this tool verify the JWT signature?
No. Signature verification requires the secret key, which should never be shared client-side. This tool decodes the header and payload only — suitable for inspecting token contents during debugging.
What is the 'exp' claim in a JWT?
'exp' is the expiration timestamp — a Unix timestamp after which the token is considered invalid. If your request is returning 401 Unauthorized, check if exp has passed. The decoder shows this as a human-readable date.
Is this free?
Yes, completely free and processes everything in your browser. Your JWT never leaves your device.
Rate this tool:
Was this tool helpful?