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Text utilities

JWT Decoder

Inspect a JWT header and payload locally, with a clear warning that decoding does not verify its signature.

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See the method

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How to use this tool

  1. Enter jwt token.
  2. Select Update result to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Split the compact token into header, payload and signature sections. Decode the first two base64url sections as UTF-8 JSON. No key lookup or signature verification is performed.

A WORKED EXAMPLE

Using jwt token = eyJhbGciOiJub25lIn0.eyJzdWIiOiJleGFtcGxlIn0., the result is { "header": { "alg": "none" }, "payload": { "sub": "example" } }. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

No. Anyone can construct a token payload. A trusted authentication system must verify the signature and all required claims before relying on it.

What to keep in mind

Only three-part compact JWTs are supported. Tokens may contain sensitive data; processing stays local and the input is not included in a share URL.

Common questions

Does a decoded token prove a user is authenticated?

No. Anyone can construct a token payload. A trusted authentication system must verify the signature and all required claims before relying on it.

Is the token sent to a server?

No. Decoding runs locally without fetching a signing key or contacting the issuer.

Methodology maintained by ClarityKit. How these tools are built and checked.