Developer tools

HTML viewer

Open HTML locally, inspect a styled preview at different screen widths, edit the source and download the original or isolated preview.

HTML source

Open an HTML file or drop it here

Choose a UTF-8 HTML file

Up to 256 KiB. Processing stays on your device.

Paste HTML, open a file or try the styled example.

Rendered preview

HTML and CSS are displayed in an isolated frame. Scripts, navigation, forms and external resources are inactive.

Preview width

Your rendered HTML will appear here after you choose Preview HTML.

Original HTML retains your source, including any scripts. The isolated preview download contains only the preview markup and its restrictive resource policy.

View HTML without uploading a file

Paste a fragment or complete document, or open a UTF-8 HTML file. Choose Preview HTML to inspect headings, tables, lists and embedded CSS. Change the preview width to check media queries. Fixed widths keep their actual CSS viewport size; use the preview area's horizontal scroll on smaller screens.

What the preview supports

Common semantic HTML, inline styles, style blocks and embedded PNG, JPEG, GIF or WebP images are supported. Scripts, event handlers, navigation URLs, external stylesheets, external images, fonts, frames, SVG, MathML and other unsupported elements are omitted or blocked. Form controls are disabled. This is a static document viewer, not a JavaScript playground. Parser notices indicate where a browser may repair markup; they do not certify valid HTML.

Source and recovery

Editing hides the old preview and disables its downloads until you preview again. Example, Clear and successful import save one Undo step with source, filename, preview width and the accepted preview. Invalid imports keep useful work. Original file line endings and any UTF-8 BOM survive source export until you edit; the editor displays normalized line breaks. Source downloads may contain active code from your original file, so review them before opening elsewhere.

Limits and privacy

Use at most 256 KiB, 20,000 parsed nodes and 80 nested element levels. Preview work runs in a local worker with a ten-second cancellation deadline. No accounts, uploads or automatic storage. The preview may differ from a full website because external assets and scripts are inactive. Downloading the isolated preview preserves its static markup, CSS and resource restrictions.