🔐 JWT Decoder & Inspector

🔍 What is a JWT?

A JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. It is commonly used for authentication and authorization in web applications and APIs.

A JWT consists of three parts separated by dots (.):

• Header — Contains metadata like the signing algorithm (alg) and token type (typ).
• Payload — Contains the claims (statements about the user and additional data).
• Signature — Used to verify the token hasn't been tampered with.

⚙️ How JWT Works

1. Client logs in — Sends credentials to the authentication server.
2. Server creates JWT — Signs a token with a secret key and sends it back.
3. Client stores token — Typically in localStorage or a cookie.
4. Client sends token — Attaches it to subsequent API requests (e.g., in the Authorization header).
5. Server verifies — Checks the signature and claims, then grants or denies access.

🛠️ How to Use This Tool

1. Paste your JWT into the input area above.
2. The token is decoded automatically as you type.
3. View the Header and Payload in formatted JSON.
4. Copy individual parts or download the entire decoded JSON.
5. Review expiration and other claims in the Token Information table.

✅ Why Use This Tool?

• Debug authentication tokens during development.
• Inspect API responses that contain JWTs.
• Learn the structure of JSON Web Tokens.
• Verify token claims like expiration and issuer.
• Troubleshoot login and authorization issues.
• Perfect for web development and testing workflows.