解码和验证JWT令牌，查看Header和Payload
JWT (JSON Web Token) is a compact, URL-safe token format used for authentication and information exchange. It consists of three parts: header, payload, and signature.
This tool decodes and displays JWT contents but does not verify signatures. For signature verification, use a server-side tool with the appropriate secret key.
Yes, the tool highlights the expiration time (exp), issued at (iat), and not before (nbf) claims, and indicates if the token is expired.