Security & Crypto Tools
JWT Generator / Signer
Sign and decode JWTs with HS256, HS384, or HS512.
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What is JWT?
A JWT utility for development: sign tokens with a secret key and view the decoded payload of any token.
How it works
The header and payload are Base64URL-encoded and HMAC-signed with Web Crypto; decoding simply parses and Base64URL-decodes the payload segment.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Signing a development token
Build a JWT from a JSON payload and an HS256 secret — or paste an existing token to decode its header and payload.
Common mistakes
Signing production tokens in the browser
The signing secret would have to live client-side. Sign server-side for anything real.
Frequently asked questions
Is this secure enough for production secrets?
Signing happens locally with Web Crypto, but for production you should still sign server-side so the secret never enters a browser at all.