JWT Generator — Create & Sign a JSON Web Token
Build and sign a real JWT from a custom header, payload, and HS256 secret — the missing companion to the JWT Decoder. Free, client-side JWT generator.
🔒 100% Client-Side Processing
Your data is processed entirely in your browser and never transmitted to any server.
Common Use Cases
Testing an auth-protected endpoint
Generate a signed JWT with custom claims to exercise a login-required API route during development.
Mocking third-party auth in tests
Create tokens with a known test secret to stand in for a real identity provider in integration tests.
Frequently Asked Questions
- Which signing algorithm does this use?
- HS256 (HMAC-SHA256) only — the overwhelmingly common choice for testing and internal auth flows. RS256/ES256 need an asymmetric keypair and are out of scope for a single-secret generator like this one.
- Is the token this generates a real, valid JWT?
- Yes — it is signed using the WebCrypto crypto.subtle API with the exact HS256 algorithm real servers use, not a mock. Any library or service configured with the same secret will verify it successfully.
- Can this also decode an existing JWT instead of creating one?
- Not on this page — this tool only builds and signs new tokens. Use the JWT Decoder to inspect the header and payload of a token you already have.
- Is my data private when I use this tool?
- Yes. This tool runs entirely in your browser using client-side JavaScript — nothing you type is transmitted to, logged by, or stored on any server. You can safely process confidential text, tokens, or code.