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🔓 JWT Decoder
Decode JWT header and payload safely in your browser. Inspect claims and structure without sending tokens anywhere.
JWT Decoder
Decode JSON Web Tokens (JWT) into their header, payload, and signature parts. Useful for debugging authentication tokens. ⚠️ Decoding does not verify signatures — everything runs locally in your browser.
Header
—
Payload
—
Signature
—How to use this tool
- Paste a JWT into the input field.
- Review the decoded header and payload JSON.
- Copy any section or reset the form when finished.
Debug scenarios
- Inspect claims when troubleshooting authentication issues.
- Verify audience, issuer, and expiration fields before deploying changes.
- Teach teammates how JWTs are structured without exposing secrets.
Security reminders
- Decoding does not prove the token is trustworthy—always verify signatures server-side.
- Never paste tokens from production environments into untrusted tools.
- Use short-lived tokens and rotate secrets regularly to minimize exposure.
FAQ
- Why is the signature unreadable?
- Signatures are binary data represented as base64url strings. They can't be decoded to JSON because they aren't meant to be human readable.
- Can I verify the signature here?
- No. This tool only decodes. Use the JWT Generator/Validator or server-side libraries to verify signatures.
- Is decoding offline?
- Yes. All parsing happens locally in your browser—tokens are never transmitted.
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