JWT Decoder
JWT Decoder
Decode any JWT token to inspect its header and payload claims without needing the signing secret.
How to Use JWT Decoder
- 1.Paste the JWT Paste the full JWT token (three Base64url-encoded parts separated by dots).
- 2.Inspect header and payload The header (algorithm, type) and payload (claims, expiry) are decoded and displayed as formatted JSON.
- 3.Check expiry and claims exp, iat, and nbf timestamps are converted to readable dates automatically.
- 4.Copy decoded sections Copy the decoded header or payload JSON for use in debugging.
JWT Decoder & JSON Developer Standards
JSON is the standard format for web APIs and modern applications. Using the JWT Decoder helps you check syntax, catch formatting errors, and keep your data clean and readable.
Zero-Server Security
All data entered into JWT Decoder runs directly inside your browser sandbox. Nothing is ever sent across the network or saved on remote servers.
Clean & CI/CD Ready
Well-formatted JSON prevents runtime syntax bugs, makes code reviews easier, and ensures smooth API data exchange.
JWT Decoder Frequently Asked Questions
Is it safe to paste a JWT here?
The decoder runs entirely in your browser - your JWT is never sent anywhere. However, treat JWTs as sensitive tokens and avoid pasting production tokens with long lifetimes into any online tool.
Does the decoder verify the JWT signature?
No. The decoder only decodes the Base64url-encoded header and payload. It does not verify the signature, which requires the signing secret or public key. Use this tool for inspection only, not for security validation.
What are JWT claims?
Claims are key-value pairs in the JWT payload. Standard claims include: iss (issuer), sub (subject), aud (audience), exp (expiry time), nbf (not before), iat (issued at), and jti (JWT ID). Custom claims are any additional properties added by the issuing application.
What algorithms does the header alg field refer to?
Common values: HS256 (HMAC-SHA256, symmetric), RS256 (RSA-SHA256, asymmetric), ES256 (ECDSA-SHA256, asymmetric). HS256 uses a shared secret; RS256 and ES256 use a public/private key pair.
Why is my token showing as invalid?
Ensure you are pasting the complete token including all three parts separated by dots. If the token was copied from a URL, check that URL encoding (such as %3D instead of =) has not been included.
Can this tool handle large, complex JSON payloads?
Yes. Because the tool operates directly inside modern V8 JavaScript execution engines, it easily processes complex multi-megabyte payloads containing thousands of nested keys with negligible latency.
Are my proprietary payloads or secrets stored or cached?
No. BeYourTools implements zero tracking, zero telemetries, and zero database persistence. Everything stays strictly inside your browser memory and disappears the moment your tab is closed.