JWT Generator & HMAC Signer
Generate and sign JSON Web Tokens (JWT) using HMAC-SHA256, HMAC-SHA384, or HMAC-SHA512. 100% in-browser Web Crypto security.
Batch workspace
Format multiple files locally in one run.
How to use the JWT Generator
Paste code or file
Paste your raw JSON text or upload directly.
Configure options
Choose indentation, dialect, or formatting preferences.
Format & export
Click format, then copy, download, or inspect in tree view.
What is a JWT Generator?
Generate and sign JSON Web Tokens (JWT) using HMAC-SHA256, HMAC-SHA384, or HMAC-SHA512. 100% in-browser Web Crypto security. This tool re-indents and organizes code according to standard style conventions while checking for syntax validity. Everything executes 100% inside your browser, guaranteeing zero latency and complete privacy for API keys, user tokens, and confidential database schemas.
Options Explained
| Option | Description |
|---|---|
| Signing Algorithm | Cryptographic HMAC hash algorithm used to sign the token payload. |
| Expires In (Seconds) | Token validity duration added to exp claim (0 for no exp claim). |
Frequently Asked Questions
How does this tool sign JWT tokens without a backend server?
It uses the browser's native Web Crypto API (crypto.subtle.sign) with HMAC keys. All cryptographic signing happens locally in memory.
Which signing algorithms are supported?
HMAC-SHA256 (HS256), HMAC-SHA384 (HS384), and HMAC-SHA512 (HS512) symmetric signing algorithms are supported.
Are secret keys sent to any external server?
Never. Your payload and secret keys never leave your browser window.
Does this tool automatically add iat and exp claims?
Yes. By default, it automatically populates standard 'iat' (issued at) and calculates 'exp' (expiration) timestamps.
Is my data uploaded when I use the JWT Generator?
No. All processing runs entirely in your browser. Nothing is sent to a server unless you explicitly create a share link.