JWT Debugger & Decoder
Our JWT Debugger & Decoder is an indispensable tool for developers working with modern web authentication. JSON Web Tokens (JWT) are the backbone of secure data transmission between clients and servers, but their encoded format can be difficult to inspect manually. This tool allows you to instantly decode any JWT to view its header, payload, and claims without needing a secret key. It's perfect for verifying token expiration, checking user roles, and debugging complex OAuth2 or OpenID Connect flows. T00LZ processes everything locally, ensuring your sensitive authentication tokens are never exposed to external servers.
Token details will appear here after decoding
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Ever found yourself needing to 'look inside' a secure token but were only met with a wall of encoded text?
Imagine you're trying to debug an authentication issue and have a messy JWT (JSON Web Token) that doesn't tell you why your user can't log in. Our JWT Debugger is like a digital X-ray, instantly splitting your token into its Header, Payload, and Signature. It lets you see exactly which user ID and permissions are inside, saving you from the headache of manually decoding Base64 strings, while keeping the technical details clean and organized.
Think of this as your private audit station—how can I verify my token's expiration and user claims?
Imagine you're checking a critical production token that contains sensitive user data—you wouldn't want those secrets being sent to a third-party server. That's why our JWT tool runs 100% 'client-side.' Every bit of the decoding happens right inside your own browser window. You can check the 'iat' and 'exp' fields for total accuracy, ensuring your tokens are fresh and secure, without ever risking your developer secrets.
Does this tool let me verify the actual cryptographic signature of the token?
Think of this as a highly skilled 'inspector' rather than a final gatekeeper. While our tool decodes the content so you can read it, true signature verification requires your server's private secret or public key. For your protection, we recommend performing the final verification on your own server. Our debugger is designed to help you *understand* the token's structure and contents first, providing the clarity you need to build more secure authentication flows.