Free JWT Signer Online — No Signup Required
JWT Signer helps you Create HS256 JWT tokens from a payload, headers, and secret — test auth flows without a backend — free, in 2026, without leaving the browser. It is built for developers, analysts, and privacy-conscious teams, so you can securely encode, decode, compare, or inspect sensitive values with a fast public URL, clear output, and a workflow that stays focused on the task instead of setup.
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What is JWT Signer?
A JWT Signer lets you create signed JSON Web Tokens (JWTs) from a header, payload, and secret or private key. JWTs are the standard format for authentication tokens in APIs, OAuth flows, and microservices — the signature proves the payload has not been tampered with since it was issued. Signing a token manually is useful when testing API endpoints, generating test credentials for staging environments, or debugging token validation failures without standing up a full auth server.
This tool signs in the browser using the Web Crypto API, which means your secret key and payload never leave your device. Supported algorithms include HS256 (HMAC with SHA-256, shared secret), RS256 (RSA with SHA-256, private key), and ES256 (ECDSA with P-256). The output is a standard three-part JWT you can paste directly into an Authorization header or decode with a JWT decoder to verify the contents.
- 1
Enter your payload
Paste a JSON object with your claims — user ID, role, expiry (`exp`), and any custom fields your API expects.
- 2
Choose the algorithm and enter your secret
Select HS256 for a shared secret or RS256/ES256 for asymmetric keys. Paste the secret or private key.
- 3
Copy the signed token
Click Sign to generate the JWT. Copy the result and use it as a Bearer token in API requests or test suites.
- Signs tokens in the browser — secret never uploaded to a server
- Supports HS256, RS256, and ES256 algorithms
- Instant output — no auth server or library setup required
- Useful for API testing, debugging, and staging credential generation
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JWT Signer FAQs
Quick answers about the workflow, privacy, and where this tool fits in a broader job.
Is it safe to sign JWTs in the browser?
For testing and development, yes — signing happens locally using the Web Crypto API, so your secret key is never transmitted anywhere. For production token issuance, sign on your server to keep the secret protected at the infrastructure level.
What is the difference between HS256 and RS256?
HS256 uses a single shared secret for both signing and verification. RS256 uses a private key to sign and a public key to verify, which allows API consumers to verify tokens without accessing your signing secret.
How do I verify a token I just signed?
Use the JWT Decoder tool to paste the token and inspect the header and payload. To verify the signature, paste the same secret or public key used during signing — the decoder confirms whether the signature is valid.
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Tested in Chrome, Firefox, and Safari on desktop and mobile.