Which HMAC signing algorithms are supported?

Supports HS256 (HMAC-SHA256), HS384 (HMAC-SHA384), and HS512 (HMAC-SHA512) via the native browser Web Cryptography API.

Are my signing secrets kept secure?

Yes! All cryptographic signature generation executes 100% locally in your browser. Secrets and payload data are never sent to any server.

Fast, Private & Client-Side Developer Suite

100% Client-Side • Private

Cryptography

Create and sign custom JWT tokens with HMAC-SHA256, expiration, and payload claims.

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Decode JWTs and sign or verify HS256, HS384, and HS512 tokens locally

Generate RSA and ECDSA public/private key pairs in PEM format securely in browser

Generate and verify OAuth PKCE S256 verifier and challenge pairs

Select the HMAC algorithm (HS256, HS384, HS512) and type your signing secret key.
Edit the Header and Payload JSON objects with your desired claims and payload data.
Click "+ Add exp" if you need a standard 1-hour expiration timestamp.
Copy the generated 3-part encoded and signed JWT token.

Which HMAC signing algorithms are supported?: Supports HS256 (HMAC-SHA256), HS384 (HMAC-SHA384), and HS512 (HMAC-SHA512) via the native browser Web Cryptography API.
Are my signing secrets kept secure?: Yes! All cryptographic signature generation executes 100% locally in your browser. Secrets and payload data are never sent to any server.

Review policy: references and behavior notes are checked whenever the tool implementation changes.