JWT Decoder
Decode and inspect JWT (JSON Web Token) headers and payloads. All decoding happens in your browser — no data is sent anywhere.
What is a JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information as a JSON object. It's commonly used for authentication and authorization in web applications.
Structure: header.payload.signature — three Base64URL-encoded parts separated by dots.
⚠️ Security note: This tool only decodes publicly readable header and payload data. It does not validate the signature. Never trust decoded claims without proper server-side signature verification.
All decoding happens locally in your browser. Your token is never sent to any server.