Skip to main content
Toolzum
Back to Developer

HTML Preview

Write HTML and see a live preview rendered in a sandboxed iframe. Perfect for prototyping and testing. Code never leaves your device — formatting and validation run locally in your browser.

100% Local Browser Native

How to Use the HTML Preview

1. Paste HTML markup

Full documents or snippets with inline styles.

2. Watch the live preview

Rendering updates as you type; open DevTools thinking for layout bugs.

3. Copy or export

Copy the markup back out or screenshot the preview for docs.

Similar Tools You Might Need

See all

Border Radius Generator

Generate CSS border-radius values visually. Control each corner independently with live preview. Code never leaves your device — formatting and validation run locally in your browser.

Open Tool

Flexbox CSS Generator

Generate Flexbox CSS code interactively. Configure direction, wrap, justify, align, and gap with live preview. Code never leaves your device — formatting and validation run locally in your browser.

Open Tool

CSS Grid Generator

Generate CSS Grid layout code interactively. Configure columns, rows, and gap with live preview. Code never leaves your device — formatting and validation run locally in your browser.

Open Tool

Markdown Previewer

Preview Markdown as rendered HTML on demand — headings, pipe tables, code, lists, and links sanitized with DOMPurify. Write docs seeing final output — local rendering, free, no signup.

Open Tool

SVG Editor

Edit SVG code with live preview — paths, fills, transforms. Tweak icons without Illustrator — local editing, unlimited saves.

Open Tool

Frequently Asked Questions

How does the live preview work?

As you type HTML in the editor, the preview pane updates in real-time using an iframe. The HTML is rendered immediately without any build step.

Is the preview sandboxed?

Yes. The preview runs in a sandboxed iframe that prevents it from accessing the parent page or running scripts that could affect the editor.

Can I use external CSS/JS?

Yes. You can include external stylesheets and scripts via URL in the HTML. They load from their sources in the sandboxed preview.

Does it auto-refresh?

Yes. The preview updates automatically as you type. There's no manual refresh button needed — changes appear instantly.

Is my HTML uploaded?

No. All rendering happens locally in your browser. No HTML data is sent to any server.

What are the exact preview sizes and save name?

Desktop renders at 100% width, Tablet at 768px and Mobile at 375px. Auto-refresh waits 300 ms after each keystroke (turn it off for a manual Refresh button); the iframe sandbox is exactly allow-scripts, both panes are 500px tall, and Download saves output.html.

Related Developer Tools

HTML Formatter

Indents and structures HTML markup with proper nesting, attribute alignment, and readable indentation for templates and email designs.

HTML to JSX Converter

Converts HTML files to JSX format — web pages, email templates, and content rendering to React component definitions and UI rendering. All conversion happens locally in your browser with no file size limits.

Last updated October 2026