HTML Viewer

Paste HTML to preview it live in a sandboxed iframe. JavaScript is executed safely in an isolated context.

HTML Source
Preview
Height:
Your HTML preview will appear here

Privacy & Security

HTML is rendered entirely in your browser using a sandboxed iframe with sandbox="allow-scripts". The preview runs in a null origin — completely isolated from this page's cookies, localStorage, and DOM. No data is sent to any server.

Tips

  • • The preview updates automatically as you type
  • • Use the height buttons to adjust the preview area
  • • JavaScript inside your HTML runs in a sandboxed, isolated context
  • • Forms and external navigation are blocked by the sandbox

About the HTML Viewer

The HTML Viewer lets you paste and instantly preview any HTML document directly in your browser. It uses a sandboxed iframe so JavaScript in your HTML runs safely, isolated from the rest of the page.

Features:

  • Live preview as you type
  • Full HTML5 + CSS support
  • JavaScript execution in a sandboxed context
  • Adjustable preview height (300 – 800 px)
  • Load a built-in example to get started
  • Copy HTML to clipboard

Common Use Cases:

  • Quickly prototype HTML snippets
  • Preview email templates
  • Debug CSS layouts
  • Test interactive JavaScript components
  • Share rendered HTML without a hosting environment

Security note: The preview iframe uses sandbox="allow-scripts" without allow-same-origin, so rendered code runs in a null origin and cannot access this page's cookies, localStorage, or DOM. Network requests (fetch, XHR) from the iframe are still allowed, so treat pasted HTML from untrusted sources with care.