JWT Encoder

How to use JWT Encoder

1. Open JWT Encoder — it runs entirely in your browser with no setup.
2. Paste or type your input into the text area, or upload a file where supported.
3. Set any options you need. The result appears in the output panel — there is no upload step and no waiting on a server.
4. Review the output instantly; large inputs are handled locally without lag.
5. Copy the result to your clipboard or download it. Your data never leaves the page.

Why use JWT Encoder?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full developer tools suite, so related jwt encoder tasks are one click away.

What people use JWT Encoder for

• Creating a signed test token for local development against an API.
• Reproducing a token with specific claims to test authorisation logic.
• Checking that your service accepts the claim structure you intend to issue.

JWT Encoder: limits and things worth knowing

• HS256 signs and verifies with the same shared secret, so anyone who can verify a token can also mint one. RS256 uses a private key to sign and a public key to verify, which is what you want when the verifier is a different party.
• A short or guessable HMAC secret makes the signature brute-forceable offline. Use a long random secret, not a word.
• Always set exp. A token without an expiry is valid forever, and revoking one requires infrastructure that most services do not have.
• The secret you type stays in your browser. Signing a token in a server-side tool means handing over your signing key.

Sources

• RFC 7519 — JSON Web Token (JWT)

Is it private and secure?

Your privacy is built in. JWT Encoder runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Is It Safe to Paste Production Data Into Online Tools? — JWTs, API responses and env files get pasted into online formatters every day. Here's what actually happens to that data and how to check before you paste.