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JWT Decoder / Inspector

Decode and inspect JSON Web Tokens. View Header, Payload, and Signature. Expiration status, algorithm label, and one-click copy per section.

Developer Tools Runs locally No data sent
decode jwt authentication client-side
JWT Token
Awaiting token—
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Paste a JWT to decode
Supports HS256, RS256, ES256 and all standard JWT algorithms

What is JWT Decoder?

JWT Decoder parses JSON Web Tokens into their three parts so you can inspect the header, payload claims, algorithm, and signature segment. It is useful for authentication debugging, expiry checks, and understanding what a token actually contains without sending it to a server.

How to Use JWT Decoder

  1. Paste the JWT into the input area.
  2. Review the decoded header and payload sections.
  3. Inspect claims such as exp, iss, aud, sub, and custom fields.
  4. Copy the decoded values or compare them with your auth flow expectations.

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Understand JWTs ▾
Example
Input Paste a JWT such as eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
Output The tool splits the token into header, payload, and signature, then decodes the readable claims.
Common Use Cases
  • Inspect token claims during API and auth debugging
  • Check expiry, issuer, audience, and subject values without backend tooling
  • Confirm which signing algorithm and token structure a system is using
  • Teach how JWT header, payload, and signature segments fit together
Why Use This Tool
  • Helps debug login flows, API authorization, and token expiry issues.
  • Makes JWT structure easier to explain to teammates and stakeholders.
  • Runs locally so pasted tokens are not uploaded during inspection.
Frequently Asked Questions
Is it safe to paste my JWT here?

Yes. Decoding runs entirely in your browser, and the token is never sent to a server. That said, avoid pasting production tokens with sensitive claims into any public tool unless you are certain it is client-side only.

Can this tool verify the signature?

No. Signature verification requires the secret (HMAC) or public key (RSA/EC). This tool only decodes the Base64URL-encoded header and payload; verification must happen on your server.

What does token expired mean?

The exp claim is a Unix timestamp indicating when the token stops being valid. If the current time is past that timestamp, the server will reject the token and you will need to re-authenticate.

What is the difference between JWT and session cookies?

Session cookies store a session ID on the server and look it up on each request. JWTs are self-contained: all claims are in the token itself, so no server-side session storage is needed. This makes JWTs useful in stateless, distributed systems.