JWT generator (HS256/384/512)
Generate and sign a JWT (HS256/384/512) from a payload and secret, in your browser.
HMAC signature computed locally (Web Crypto). Your secret never leaves your browser.
🔒 100% client-side — no data sent
Create and sign a JSON Web Token from a payload and a secret, using the HS256, HS384 or HS512 algorithms. The signature is computed right in your browser, so your secret never leaves your machine.
What is it for?
- ▸ Generate a test token to call a protected API
- ▸ Check that a payload produces the expected signature
- ▸ Reproduce a JWT to debug an authentication flow
- ▸ Learn how HMAC-signed tokens actually work
FAQ
Is my signing secret sent anywhere?
No. The token is signed locally in the browser; neither the secret nor the payload is sent to a server.
What is the difference between HS256, HS384 and HS512?
They all use HMAC with a shared secret, but different SHA hash functions (256, 384 or 512 bits). HS256 is the most common.
Can I generate an RS256-signed JWT?
This tool covers the symmetric HMAC algorithms (HS256/384/512). Asymmetric signatures like RS256 require a key pair and are not supported here.