HTML VIEWER GUIDE

Preview HTML, CSS and JavaScript online

HTML Online Viewer is a browser-based code editor for writing, testing and troubleshooting a web page with an instant live preview. Use separate HTML, CSS and JavaScript files, inspect errors and console output, then export everything as one HTML document.

Start editing HTML

What can the online HTML viewer do?

An HTML code viewer may also be described as an online HTML editor, HTML renderer or HTML tester. In each case, the goal is the same: turn source code into a working browser preview quickly enough to experiment and fix problems.

Live HTML preview

Paste or write HTML and see the rendered result update while you type without repeatedly refreshing the page.

HTML, CSS and JS editor

Keep markup, styles and JavaScript in separate tabs while the viewer combines them safely in the preview.

HTML validation

Find malformed tags and attributes with visible line markers, then jump directly to the reported HTML error.

Format and minify HTML

Beautify readable source or preview a minified version with the original size, new size and percentage saved.

Responsive preview

Test the same page at desktop, tablet and phone widths without leaving the online editor.

Console and resource errors

Read JavaScript logs, warnings, runtime errors and failed image or script requests alongside the preview.

How to test HTML code online

  1. 1
    Add the page structure

    Open index.html and paste a complete HTML document or a small HTML fragment.

  2. 2
    Add styles and behavior

    Use styles.css for CSS and script.js for JavaScript. The live preview combines all three automatically.

  3. 3
    Inspect the result

    Choose desktop, tablet or phone preview, then open the console to check logs and failed resources.

  4. 4
    Clean and export

    Format the source for readability, compare minified HTML sizes, and download a self-contained index.html.

Frequently asked questions

What is an HTML viewer online?

An online HTML viewer renders HTML code directly in a web browser. A live HTML editor also lets you change the source and immediately see how the page responds.

Can I preview HTML, CSS and JavaScript together?

Yes. This viewer provides separate source tabs and combines their contents inside one isolated live preview.

Does the editor upload my code?

The editor stores the working files and version history in local browser storage. The preview is sandboxed and the exported file is generated on your device.

What is the difference between formatting and minifying HTML?

Formatting adds consistent indentation and line breaks for people to read. Minification removes unnecessary bytes for a smaller production file. The viewer shows the size comparison before applying minification.

How do I find an HTML error?

Open Problems to see parsing and preview errors. HTML syntax issues include a line and column and can be selected to move the editor to that location.

Can I recover code after formatting or clearing it?

Yes. Version history saves local snapshots before destructive actions including format, minify, clear, import and Replace all.