JWT Generator | Securely Create & Sign Tokens Offline

Generate and sign JWTs for API testing. Edit header and payload, use HS256/HS384/HS512, and keep your secret local while HMAC signing runs in the browser.

Click for theater mode

JWT Signer

Secret, header, and payload are not uploaded.

Quick exp

Edit JSON and the secret to sign a token automatically.

Generated JWT

How to Use

  1. Click "Load Example" to start with an API testing payload such as sub, role, and exp.
  2. Choose the algorithm in the Header panel. HS256 is selected by default, with HS384 and HS512 available.
  3. Edit the Payload JSON. Use "In 1 hour" to write a valid exp timestamp quickly.
  4. Enter a test secret in the Verify Signature panel. Use "Show / Hide" when you need to verify the value.
  5. Copy the token and paste it into an Authorization: Bearer header for API testing.

Core Features

  • Local Secret-Safe Signing: Your secret is sensitive. HMAC signing runs in the browser with Web Crypto API, without sending the secret, header, or payload to a server.
  • Live Token Preview: Edit the header, payload, algorithm, or secret and the final JWT updates automatically.
  • HMAC Algorithms: Supports HS256, HS384, and HS512 for common development and API testing workflows.
  • Quick Expiration Claims: Set exp to 1 hour, 1 day, or 7 days from now with one click.
  • Show or Hide Secret: Toggle secret visibility while typing so you can confirm a test key without permanently exposing it.

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Calculation Logic

  • A JWT contains three parts: header.payload.signature.
  • This tool serializes the header and payload as compact JSON, then Base64Url-encodes both parts.
  • The signature is produced locally with the browser Web Crypto API by running HMAC-SHA over header.payload.
  • This tool is intended for development and testing. Even with local signing, do not paste production secrets into third-party websites.

FAQ

Is it safe to paste my JWT secret here?

Signing runs locally in your browser and the tool does not upload the secret, header, or payload. Still, security best practice is to use development, test, or temporary secrets only.

Can I reveal the secret while typing?

Yes. The Secret field includes a Show / Hide toggle so you can verify a test secret without leaving it visible.

What algorithms are supported?

This version supports HMAC algorithms: HS256, HS384, and HS512. RS256 requires private-key parsing and asymmetric signing, so it is not promised here.

How can I set token expiration?

Add an exp claim using a UNIX timestamp in seconds. The quick buttons can set it to 1 hour, 1 day, or 7 days from now.

Can I use the generated JWT in production?

Use it for local development, API integration tests, and debugging. Production tokens should be issued by trusted backend infrastructure.