⚙️ WasmTools

JWT Decoder Online — Inspect Header & Payload

Free online JWT decoder: view the header, payload claims, and expiry of any JSON Web Token. Decoded 100% locally in your browser — the token never leaves your device.

Loading WebAssembly engine…

Use it in your terminal (or let an AI agent run it)

This tool also ships as a command-line version in the wasm-tools-cli npm package — the exact same engine as this page, running locally on your machine.

cat token.txt | npx wasm-tools-cli jwt decode
🔒 Runs entirely in your browser — your files never leave your device.

About JWT Decoder

JWT Decoder is a free online data tool that runs entirely in your browser. There is nothing to install and no account to create: open the page, use the tool, and download the result. Because all processing happens locally on your device (via WebAssembly), your files and text are never uploaded to any server.

How to use JWT Decoder

  1. Paste or type your content into the input box.
  2. Choose the operation (and any options) and click the corresponding button.
  3. Copy the result or download it as a file.

Frequently asked questions

Is JWT Decoder really free?

Yes — JWT Decoder is completely free, with no account, no watermark, and no usage limits. It runs entirely in your browser.

Are my files uploaded to a server?

No. All processing happens locally on your device using WebAssembly. Your files never leave your computer — close the tab and nothing remains.

Which browsers are supported?

Any modern browser on desktop or mobile: Chrome, Firefox, Safari, and Edge.

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