JWT Decoder: Decode and Inspect JWT Tokens

JWT (JSON Web Tokens) are widely used for authentication and authorization in modern web applications. Our JWT Decoder helps you decode and inspect JWT tokens, viewing the header, payload, and signature components. Understanding JWT contents is essential for debugging authentication issues, verifying token claims, and ensuring proper security configuration. Perfect for developers working with APIs, authentication systems, and JWT-based security.

How it works

1. Paste a JWT token into the decoder (JWT tokens have three parts separated by dots).
2. The tool decodes the Base64-encoded header and payload sections.
3. Header information is displayed, showing the algorithm (HS256, RS256, etc.) and token type.
4. Payload claims are decoded and displayed, including standard claims (iss, exp, sub) and custom claims.
5. Token validity can be checked, including expiration times and signature verification status.

Why it matters

• Debug authentication issues by inspecting token contents and verifying claims.
• Verify token expiration and validity to ensure security is working correctly.
• Understand JWT structure and claims for better integration with authentication systems.
• Test JWT-based APIs by decoding tokens and verifying their contents.
• Learn about JWT security by seeing how tokens are structured and what information they contain.

FAQ

What is a JWT token?

JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three parts: header, payload, and signature.

Can I verify the JWT signature?

Signature verification requires the secret key or public key used to sign the token. Our tool can decode the token, but full signature verification requires access to the signing key.

What are JWT claims?

Claims are pieces of information asserted about a subject. Standard claims include "iss" (issuer), "exp" (expiration), "sub" (subject), and "iat" (issued at). Custom claims can contain any additional information.

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