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JWT Inspector

Decode a JWT and check exp, nbf and algorithm claims.

What Is a JWT Inspector?

The JWT Inspector decodes a JSON Web Token and also analyzes the claims for common issues. It reports the algorithm, type, key id, whether a signature is present, and checks the exp (expiration) and nbf (not before) timestamps, listing any problems it finds. This free online security tool is useful for JWT inspector, JWT analyzer, JWT token checker. Common use cases include checking JWT structure, claims, expiration, and common configuration issues. It is designed for quick browser-based analysis and development workflows. Security checks are signals rather than guarantees, so production systems should also be validated against current standards and their specific threat model.

How to Use This JWT Inspector

  1. 1
    Paste the JWTEnter the three-part JSON Web Token into the input field.
  2. 2
    Review the headerCheck the token type and declared signing algorithm.
  3. 3
    Inspect the payloadReview claims such as iss, sub, aud, exp, iat, and nbf.
  4. 4
    Check warningsLook for expired timestamps or suspicious configuration reported by the inspector.
  5. 5
    Remember signature validationDecoding and structural inspection do not prove that a token is authentic.

Frequently Asked Questions

It means the token was not signed. Accepting unauthenticated tokens is a serious security issue, which this tool flags.
An expiration claim limits how long a stolen token remains usable. Without it, a token could be valid indefinitely.
No. It inspects structure and timestamps only. Signature validation requires the issuer's key, which the tool cannot know.

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