JWT Builder
Build and sign JSON Web Tokens with custom headers, payloads, and secrets. Instant preview of the encoded token. Runs entirely in your browser — your secrets never leave your machine.
🔐 HS256 signing
Signs tokens using HMAC-SHA256 with your secret. The same algorithm used by most production auth systems.
⚡ Instant preview
Token updates as you type. See the three-part structure — header, payload, signature — change in real time.
🔒 100% private
Your secret never leaves your browser. No server, no logs, no third parties. Safe for real secrets.
How to use the JWT Builder
Build a signed token
Edit the Header and Payload fields with your desired claims. Set your secret in the Signature panel and choose an algorithm. Click Build Token — the encoded token appears instantly with each section color-coded: blue for header, purple for payload, green for signature.
Add claims quickly
Use the claim preset buttons below the payload editor to add standard claims in one click — iat (issued at), exp (expiry), jti (unique ID), and more. Timestamps are set automatically based on the current time.
Verify your token
Click Verify in Debugger to carry the token directly into the JWT Debugger tool. The encoded token is copied to the debugger automatically — no tab switching, no manual paste.