Simple HTML Viewer is a VS Code extension for rendering interactive HTML documents directly inside the editor without relying on a localhost preview server.
It is built for HTML files that need real browser behavior inside VS Code: embedded JavaScript, third-party widgets, saved web pages, and local asset folders.
Why Simple HTML Viewer?
Preview HTML inside VS Code without spinning up a local web server.
Render interactive content such as Plotly charts, sortable tables, and embedded JavaScript.
Control preview zoom independently from VS Code application zoom.
Use the same preview workflow in local workspaces and Remote-SSH sessions.
Features
Open previews from the command palette, editor title, explorer context menu, or Open With....
Zoom toolbar with -, current zoom percentage, +, and reset.
Auto-refresh on save by default.
Manual refresh mode when auto-refresh is disabled.
Rewrites local resource references for VS Code webviews while still allowing remote CDN assets.
Handles responsive widgets that need relayout on zoom changes.
Remote-friendly design that does not depend on forwarded localhost ports.
Usage
Open any .html or .htm file and use one of these entry points:
Simple HTML Viewer: Open Preview from the command palette
simpleHtmlViewer.activeContent: controls whether previewed HTML can run scripts and load remote resources. The default, trustedWorkspaces, allows active content only when the workspace is trusted.
simpleHtmlViewer.allowInsecureContent: allows http: and ws: resources in active previews. This is disabled by default.
Notes
HTML previews can execute scripts and contact remote URLs when active content is enabled. Keep the default workspace-trust gate unless you trust the files you are opening.
Very wide or fixed-width HTML documents may still require horizontal scrolling at larger zoom levels.
The toolbar is injected into the preview document, so extremely aggressive page-level CSS can still affect its presentation.
The current zoom model is optimized for Chromium-based VS Code webviews and may render some third-party widgets slightly differently than a standalone browser.
Saved web pages still depend on whatever companion assets were captured with them. If a saved page is missing fonts, images, or scripts on disk, the preview cannot recreate those files.
Development
npm install
npm run check
npm run test
npm run test:smoke
npm run package:vsix
Press F5 in VS Code to launch an Extension Development Host.
