How to use the HTML Viewer
This tool provides an instant, secure sandbox to test your HTML, CSS, and JavaScript. Everything runs entirely in your browser, meaning your code is never sent to any server.
Real-time Preview
As you type or paste code into the left panel, the iframe on the right updates automatically. We use a short delay to prevent the preview from flickering while you're actively typing.
Full Screen Mode
Building a responsive layout? Click the Full Screen button to expand the preview to fill your entire monitor. This allows you to accurately test media queries and viewport units. You can exit full screen at any time using the floating button.
Security
The preview renders inside an isolated <iframe> using the sandbox attribute. Scripts are allowed to run so your JavaScript functions work, but the iframe is completely detached from the main AsapGuide domain, preventing cross-site scripting (XSS) risks.