local-only

HTML / JS Sandbox

Run HTML, CSS and JS in a safe sandboxed preview.

🔒 local memory only
Initializing HTML / JS Sandbox in local browser environment…

How to use HTML / JS Sandbox

  1. Write or paste HTML, CSS, and JavaScript in the left code panel.
  2. Click "Run ▶" to execute and render the code in the sandboxed preview frame.
  3. Test animations, responsive styling, and UI components safely.

Why use this local-first tool?

  • Uses isolated sandbox iframe attributes (sandbox="allow-scripts") to run code safely without touching the host document.
  • Network requests are disabled in the sandbox for zero telemetry leakage.

Frequently Asked Questions

Can scripts in the sandbox access my cookies or host session?

No. The iframe runs in a strict unique origin sandbox without allow-same-origin, preventing any access to parent document memory or storage.

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