JWT Decoder & Debugger

What is a JSON Web Token (JWT)?

A JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.

How to Use This Tool

1. Paste your encoded JWT into the Encoded Token box on the left.
2. The tool will instantly decode the token and display its three parts—Header, Payload, and Signature—on the right.
3. Review critical payload claims like iat (Issued At) and exp (Expiration Time) which are automatically converted to human-readable dates for convenience.

Security & Privacy

Like all FreeToolSpace tools, this JWT Decoder operates entirely inside your browser. Your tokens are never uploaded, sent over the network, or saved to any server. You can safely decode sensitive production tokens here without risking compromise.

Understanding JWT Structure

• Header: Typically consists of two parts: the type of the token (JWT) and the signing algorithm being used (e.g., HMAC SHA256 or RSA).
• Payload: Contains the claims. Claims are statements about an entity (typically, the user) and additional data.
• Signature: Created by taking the encoded header, the encoded payload, a secret, and the algorithm specified in the header to ensure the token hasn't been altered.