JWT Decoder - Decode Header and Payload Locally
Local token inspection
JWT Decoder
Decode JWT header and payload locally without sending the token to a server.
Usage guide
Inspect JWT header and payload locally without treating them as verified
A JSON Web Token can be decoded without knowing its signing secret, but decoding is not the same as validating the signature or trusting the claims. This tool is useful for debugging token structure while keeping the token in the browser.
How to use JWT Decoder
- 1.Paste a JWT only when it is safe to inspect on the current device.
- 2.Review the decoded header for algorithm and key metadata, then inspect payload claims such as issuer, audience, subject, and expiration.
- 3.Validate the signature and claim rules in your application or trusted library before accepting the token for authentication or authorization.
Examples
- Check whether exp is in the past when troubleshooting an expired session.
- Compare aud and iss values with the values expected by an API gateway.
- Inspect custom claims while debugging role or tenant information.
Limitations and notes
- JWT payloads are usually encoded, not encrypted, so sensitive information should not be placed in them merely because the token looks opaque.
- Never use a decoded token alone as proof that the issuer or claims are authentic.
Does decoding verify the JWT signature?
No. Decoding only reads the Base64URL-encoded sections. Signature verification requires the correct key and validation rules.
Is it safe to share a JWT?
Often no. Many JWTs are bearer credentials. Treat real authentication tokens like passwords and avoid sharing them in tickets, chat messages, or screenshots.
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How the jwt decoder works
Paste or enter the code, data, or value you want to inspect.
The tool processes it locally in your browser.
Copy the formatted output or converted value for your project.
Frequently Asked Questions
Is the jwt decoder free?
Yes. It is free and does not require an account.
Is my code sent to a server?
No. These developer tools run locally in your browser.
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