Preview HTML in a sandbox

How to use this tool

1. Enter HTML and any inline CSS.
2. Refresh the preview to inspect its structure.
3. Account for blocked features before copying/saving sanitized HTML.

Render the heading, remove the script

Input and settings

<h1>Hello</h1><script>alert(1)</script>

Result

Hello heading rendered · script not executed

This does not test JavaScript behavior of a live application.

Processing rules and reading the result

Resource elements/URL-opening attributes are neutralized before DOMPurify allowlisting. Output uses an isolated iframe running only its hash-authorized renderer; CSP blocks connections, images, nested frames and form submission. Inline CSS is allowed only to inspect layout.

Limits and checks before use

Input and sanitized HTML are each limited to 200,000 characters. External CSS/fonts/images, SVG, embeds, forms and supplied scripts are removed or shown as text, so output may differ from the original site. Sanitized output is not a security certification.

Common questions