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UtilityBox – Free Online Utility Tools

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HTML Online Viewer

Write or paste HTML and see a live preview instantly.

HTML Online Viewer — Preview HTML Instantly, Free

UtilityBox's HTML Online Viewer is a free, browser-based tool that lets you write or paste HTML and see a live preview instantly — no server, no installation, no sign-up required. The split-panel interface puts your editor on the left and a real-time rendered preview on the right, updating as you type. Whether you are prototyping a landing page, testing a CSS snippet, or reviewing an HTML email template, this tool renders your markup exactly as a browser would. Use the Format button to re-indent messy HTML with clean 2-space indentation, the Highlight View to open a syntax-coloured source view, or Full Page Preview to open the rendered output in a new tab at full screen. Import any local .html file into the editor with one click, or export your work as a downloadable index.html. Every operation runs entirely client-side — your HTML never leaves your device.

How to Use the HTML Online Viewer

  1. Paste your HTML code into the editor on the left, or click Import file to load a local .html or .htm file.
  2. The Live Preview panel on the right updates automatically as you type, rendering your markup in real time.
  3. Click Format to re-indent your HTML with 2-space indentation for cleaner readability.
  4. Click Full Page Preview to open the rendered page in a new browser tab at full viewport size.
  5. Click Export file to download your HTML as index.html, or Copy HTML to copy it to the clipboard.

Key Features

  • Real-time live preview — the iframe updates as you type with a short debounce
  • HTML formatter with 2-space indentation and void-element awareness
  • Syntax highlight view — colour-coded tags, attributes and values in a dark theme
  • Full page preview — open the rendered output in a new tab instantly
  • Import local .html files and export the editor content as index.html
  • 100% client-side — no server upload, no data storage, no sign-up

Common Use Cases for HTML Online Viewer

  • Prototyping HTML layouts: Quickly sketch a page structure with headings, divs and styles without spinning up a local server. See the result in real time as you type, iterate fast, then export or copy when you are happy with the layout.
  • Previewing HTML email templates: HTML emails must render correctly in browser-based clients. Paste your email template into the editor and see how it renders, check that inline styles are applied, and verify the visual structure before sending.
  • Formatting minified HTML: Received a minified HTML file that is hard to read? Click Format to expand it into a properly indented structure with one click, making it easier to review, edit, and understand the document hierarchy.
  • Learning and teaching HTML: Students learning HTML can type tags and see the rendered result immediately, without needing a local development environment. The side-by-side editor and preview make the relationship between code and output immediately clear.

Frequently Asked Questions

How does the HTML Online Viewer work?

Paste or type your HTML code in the editor on the left. The preview panel on the right updates automatically as you type, rendering your HTML just like a browser would. No server or backend is involved — everything runs in your browser.

Can I preview JavaScript inside my HTML?

Yes. The preview uses a sandboxed iframe with scripts allowed, so inline JavaScript in your HTML will execute in the preview.

How do I format HTML?

Click the Format button. The tool will re-indent your HTML using a 2-space indent, making it easier to read. Void elements such as br, img, input and meta are handled correctly and not given a closing indent.

Can I import and export HTML files?

Yes. Use Import file to open a local .html file in the editor, and Export file to download the current HTML as index.html.

Is my HTML data private?

Completely. This HTML viewer runs entirely in your browser. Your code is never sent to any server, logged, or stored anywhere. It is safe to use with internal or sensitive HTML content.