Tiny Toolkit

JWT Encoder — Generate & Sign JSON Web Tokens

Build a JSON Web Token from a custom header and payload, sign it with HS256, HS384, or HS512, and get back a ready-to-use token. Edit the payload as JSON, enter a secret, and the signature is generated in your browser using the Web Crypto API — nothing is sent to a server. Handy for testing authenticated endpoints, generating sample tokens for documentation, or understanding how JWT signing works. Note that only HMAC algorithms are supported; RS256/ES256 require an asymmetric private key.

All processing happens in your browser. No data is sent to any server.

Frequently Asked Questions

Which signing algorithms are supported?
HS256, HS384, and HS512 — the HMAC family, signed with a shared secret. RS256 and ES256 require an asymmetric private key and aren't supported here.
Is my secret sent anywhere?
No. Signing happens entirely in your browser using the Web Crypto API. Your secret and payload never leave your device.
Can I use this to generate real production tokens?
You can, since the signature is a standard HMAC-SHA JWT signature. But treat any secret you type here as compromised once pasted into a browser tool — use it for testing and development, not for signing tokens with production secrets.

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