tokenDev Tool

JWT Decoder

Decode and inspect JSON Web Tokens instantly in your browser. No data sent to servers.

inputPaste your JWT token
check_circle Token is valid
Header (algorithm & type)
Payload (claims)
Signature (cannot be verified without secret)

⚠ This tool decodes only — it does not verify the signature. Use your backend JWT library to verify authenticity.

Frequently Asked Questions

A JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. It consists of three Base64URL-encoded parts separated by dots: the header (algorithm & type), the payload (claims/data), and the signature.
Yes. All decoding happens entirely in your browser. No data is ever sent to any server. Decoding only reads the header and payload — the signature is displayed but not verified, so your secret key is never needed.
No. Verifying requires the secret key or public key used to sign the token, which should never be shared in a browser tool. This decoder only reads the header and payload claims. Use your backend JWT library (e.g., jsonwebtoken in Node.js) to verify signatures.
The exp (expiration time) claim is a Unix timestamp (seconds since Jan 1, 1970 UTC) after which the token must not be accepted. This decoder checks exp and shows whether your token is currently valid or expired.
Standard registered claims include: iss (issuer), sub (subject/user ID), aud (audience), exp (expiration time), nbf (not before), iat (issued at), and jti (JWT ID). Any additional claims are "private" or "public" claims defined by your application.

About the JWT Decoder

Paste any JSON Web Token and instantly decode its header, payload, and signature components. Shows the algorithm, expiry time in human-readable format, issued-at date, and all custom claims. Decoding is done entirely in your browser — the token is never sent to any server. Useful for debugging authentication flows and inspecting API tokens.

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