JWT Debugger & Signature Generator
Decode and debug JSON Web Tokens (JWT) payload structures, headers, and generate signature hashes side-by-side.
This interactive client-side tool is part of the NervLink Cybersecurity Suite. All analysis is verified entirely inside the local browser sandbox for maximum safety and data privacy compliance.
How It Works
- Select either Decode or Generate mode.
- In Decoder mode, paste an encoded JWT string to split it into color-coded header, payload, and signature components.
- In Generator mode, edit the header and payload JSON properties and enter a secret key to compute signature hashes using HS256, HS384, or HS512.
Primary Use Cases
- Analyzing JWT claim contents (sub, iat, exp, roles).
- Validating JWT header parameters and algorithms.
- Generating mock JWT tokens for API testing and sandbox validation.
Common Security Pitfalls
- Pasting real production secrets or active tokens onto any public helper website.
- Forgetting that client-side decoding does not prove token validity (the signature must be validated on the backend).
Frequently Asked Questions
- Is it safe to decode JWTs online?
- Our JWT decoder runs entirely locally in your browser. No token strings or secrets are sent to any remote server.
- What is the difference between JWS and JWT?
- JSON Web Signature (JWS) is the framework that secures the data, while JSON Web Token (JWT) is the actual token containing claims formatted as JSON.
References & Standards