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Build a new JSON Web Token from a header and payload, and sign it with HMAC — entirely in your browser, for testing your own JWT integrations.
Initializing JWT Studio...
Write a header and payload as JSON, choose HS256, HS384, or HS512, and enter a secret key to get back a correctly-signed JSON Web Token — computed entirely in your browser via the Web Crypto API. This is for testing and debugging your own application’s JWT handling, not for producing access to systems you don’t already control.
HS256, HS384, or HS512 — your selection always becomes the signed token’s "alg" field, regardless of what you type in the header box.
Edit the header and payload as JSON. The payload defaults to a familiar example ("sub", "name", "iat") you can replace entirely.
Your secret signs the token locally and is never logged, stored, or sent anywhere. Copy the resulting token to use in your own testing.
Everything you need to know about this developer tool
No. Signing happens entirely inside your browser using the Web Crypto API. Your secret and payload are never sent to a server.
No. The algorithm you select is always what actually signs the token — this tool cannot produce an unsigned or "none"-algorithm token, even if you type that into the header field yourself.
Only if that app is configured to trust the exact secret you used to sign it. This tool is for testing your own JWT integration, not for creating access to a system you don’t control the secret for.
Not yet — this baseline supports HMAC signing (HS256/384/512) only. Asymmetric algorithm support is a planned follow-on, since it requires careful private-key handling to do safely.
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