What is JWT Generator
The JWT Generator creates JSON Web Tokens signed with HMAC-SHA256 (HS256) using the Web Crypto API. You provide the payload claims (user ID, roles, expiration, etc.) and a secret key, and the tool produces a standard three-segment JWT string (header.payload.signature) that can be used in API authentication, session management, and OAuth flows. The signing happens entirely in your browser — the secret key never leaves your device.
The generated token follows the RFC 7519 standard and is compatible with JWT libraries in every major language. The header automatically includes {"alg":"HS256","typ":"JWT"}, and the payload is Base64Url-encoded with your specified claims. The signature is computed as HMAC-SHA256 over the encoded header and payload using your secret.
How to Use JWT Generator
- Enter your payload claims as JSON in the input panel. At minimum, include
sub (subject/user ID) and exp (expiration as a Unix timestamp). The tool adds iat (issued-at) automatically. - Provide your secret key in the options panel. This is the symmetric key used to sign the token — the same key your server uses to verify it. Use a strong, randomly generated string (at least 32 characters).
- Read the output — a three-segment dot-separated string. This is the JWT you include in the
Authorization: Bearer header of API requests. - Copy the token and use it in your API client, Postman collection, or cURL command.
Why Use JWT Generator
The most common use case is testing authenticated API endpoints. When developing or debugging an API that requires JWT authentication, you need to generate valid tokens with specific claims — a user ID, certain roles, a future expiration. Instead of hitting your auth endpoint (which may require a full login flow), you can generate a token directly with the exact claims you need.
Developers also use this tool for prototyping authentication flows before implementing token generation in their application, creating test fixtures for automated test suites, and debugging token-related issues by generating tokens with known payloads to isolate whether problems are in signing, encoding, or claim validation.
Privacy & Security
This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.
Frequently Asked Questions
Should I use this for production tokens?
This tool is designed for development, testing, and debugging. In production, token generation should happen in your application's auth service, where the secret is stored securely (in environment variables or a secrets manager, not typed into a browser). The cryptographic operation itself is identical — the difference is secret management, not algorithm.
What if I need RS256 (asymmetric) tokens?
This generator produces HS256 (symmetric) tokens where the same secret signs and verifies. For RS256 tokens (signed with a private key, verified with a public key), use the JWT RS256 Verifier tool to understand the verification side, and generate RS256 tokens using your application's JWT library with an RSA key pair from the RSA Key Generator tool.
How do I set the expiration time?
Include an exp claim in your payload as a Unix timestamp (seconds since January 1, 1970). For example, a token that expires in 1 hour would have "exp": followed by the current time plus 3600. The tool provides a helper to calculate this — enter a duration like '1h' or '24h' and it computes the timestamp automatically.