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JWT Decoder

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Code & Dev

JWT Decoder

Decode and inspect JSON Web Tokens.

Workspace

Run the tool here

Browser utility

Output

Run the workspace to see the response here.

How to use

Paste the token.
Read the header, payload and expiry claim.
Verify the signature server-side before trusting the contents.

About this tool

Decode a JSON Web Token header and payload to inspect claims and expiry. Decoding does not verify the signature.

JWT Decoder is part of the TmpMailer Code & Dev set — free browser utilities that open instantly, need no account, and pair well with a temporary-email workflow when you just need a quick result.

Common use cases

Checking which scopes a token carries.
Diagnosing an expired session.
Inspecting issuer and audience claims.

Common questions

Does decoding verify the token?

No. Anyone can decode a JWT. Only a signature check with the correct key proves authenticity.

Is it safe to paste a real token?

Treat tokens as secrets. Decode test tokens here, and rotate anything you accidentally exposed.

Why is my token invalid?

Common causes are clock skew, the wrong signing algorithm, or an audience/issuer mismatch. Check exp and nbf first.

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