About this tool
Build a signed HS256 JSON Web Token in your browser, encoding the header and payload as base64url and signing them with HMAC-SHA256 via the WebCrypto API.
Frequently asked questions
Which algorithm does it use?
Only HS256 (HMAC with SHA-256). The header is fixed to {"alg":"HS256","typ":"JWT"} and signed with your secret.
Is my secret sent anywhere?
No. The token is built and signed entirely on your device using WebCrypto, and nothing leaves the browser.