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JWT Debugger & Inspector

Decode token claims, check expiration timestamps, and verify HMAC signatures without exposing keys.

  • Runs in your browser
  • Free, no sign-up
  • No uploads

Encoded JWT Token

Algorithm:HS256Expires in 44294 hours

Decoded Header (JOSE)

{
  "alg": "HS256",
  "typ": "JWT"
}

Decoded Payload (Claims)

{
  "sub": "user_12345",
  "name": "Alice Doe",
  "admin": true,
  "iat": 1516239022,
  "exp": 1951623902
}

How to use the JWT Debugger & Inspector

  1. 1

    Paste your encoded JWT token (header.payload.signature).

  2. 2

    Inspect the decoded JSON header and claims.

  3. 3

    Optional: Enter your HMAC secret key to verify signature validity.

Features

Web Crypto Verification
Verifies HS256 HMAC signatures using the browser's native subtle crypto API.
Claim Inspection
Decodes standard exp, iat, nbf, sub, and aud timestamps into readable dates.
100% Secret-Safe
Unlike online JWT debuggers, secrets and tokens are never sent over the internet.

Frequently asked questions

Is it safe to paste production JWTs here?

Yes. This tool operates strictly inside your browser window without making network requests.

What algorithms are supported for verification?

HS256, HS384, and HS512 HMAC signatures are verified using native Web Crypto APIs.