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Professional JSON Web Token inspection. Decode header and payload claims locally and securely with zero-server exfiltration.
Safe local inspection of JSON Web Token claims.
The JWT Debugger is a vital tool for debugging modern authentication flows. It allows you to peek inside the tokens generated by your auth providers (Firebase, Supabase, Auth0) to verify expiration times, scopes, and user identifiers in a 100% client-side environment.
JSON Web Tokens (JWT) are an open, industry standard RFC 7519 method for representing claims securely between two parties. Our Professional JWT Debugger allows you to peek inside these encoded strings to verify user permissions and session integrity.
Tells the application which algorithm was used to sign the token (e.g., HS256 or RS256).
Contains the "Claims"—statements about the user such as ID, name, and expiration time.
Ensures the token hasn't been altered. This is a cryptographic hash of the header and payload.
Check the "exp" claim to ensure your authentication window is correctly configured.
JWT payloads use standardized keys (Claims) to convey metadata. Understanding these is essential for debugging authentication flows in your application.
Identifies the user or principal the token belongs to (usually user ID).
Unix timestamp after which the token is no longer valid for access.
Timestamp of when the token was generated by the authority.
Authentication tokens are highly sensitive. ZeroPingTools performs all decoding logic locally in your browser. We never transmit your token across the network, ensuring 100% privacy.
By using native atob() decoding, we ensure that the structure of your token is preserved exactly as it was generated, allowing you to trust the claims displayed in our debugger.
Decoding a JWT is not the same as verifying it. To verify a token's authenticity, you must Use your server's secret key. Our tool is a debugger and viewer designed to inspect claims without needing your private keys.
A JSON Web Token consists of three distinct parts: the **Header**, the **Payload**, and the **Signature**. This debugger separates them for you, providing a human-readable view of the JSON data buried inside the encoded string.
This is crucial for troubleshooting '401 Unauthorized' errors, verifying that your 'iat' (issued at) and 'exp' (expiry) claims are correctly set, and auditing the 'sub' (subject) or custom roles.
No. The header and payload of a JWT are simply Base64URL encoded. Anyone can decode them. You only need the secret key to verify the signature or to create a new token.
Yes. Our debugger runs entirely on your local device. We do not send your token to any server, nor do we log your activity. However, always exercise caution when handling sensitive production tokens.
The 'exp' (Expiration Time) claim identifies the expiration time on or after which the JWT MUST NOT be accepted for processing. It is represented as a Unix timestamp.
This tool is a debugger for JWS (Signed) tokens, which are the most common type. JWE (Encrypted) tokens require specific keys to even view the payload and are not currently supported.
While this tool lets you see the claims, it does not verify the signature. Validity must be checked on your server using your application's private signing key.
Many debuggers use color coding to distinguish between the Header (Red), Payload (Purple/Blue), and Signature (Green). We follow this industry-standard color schema in our visual guides.
Yes. Unlike other popular decoders, ZeroPingTools runs 100% in your browser. Your token is never transmitted to our servers, keeping your sensitive auth data private.