Preview pasted HTML in a sandbox
Is this markup safe to embed? Render it in an isolated frame instead of your page.
Tools used in this guide
The job
A snippet from a tutorial, an email template, CMS output — you want to see it without letting it touch your origin. The iframe sandbox renders with no same-origin access and scripts off by default.
Paste and render
Paste HTML up to 2 MB. The frame renders immediately; an opt-in toggle adds allow-scripts when the markup needs JS to show itself.
Worked example
Paste an email template: styles and layout render, scripts stay inert. Toggle scripts on to check a widget — it still can't read your page's cookies or DOM.
Where it stops
Sandboxing is defense-in-depth, not a guarantee — preview only markup you have reason to handle. External resources in the snippet may still make network requests.