Free HTML Viewer & Real-time Live Editor 2026

Welcome to the Code Formatter HTML Viewer – the ultimate browser-based sandbox for testing, previewing, and debugging HTML, CSS, and JavaScript code in real-time. Whether you're a seasoned developer prototyping a component, a student learning web technologies, or a content editor checking html snippets, our viewer provides an instant, secure, and accurate preview of your code exactly as it renders in the browser.

Unlike simple text editors, our live HTML playground renders your code instantly as you type. This immediate feedback loop is crucial for modern web development, allowing you to experiment with layouts, styles, and interactions without the hassle of saving files and refreshing browser tabs. It works entirely client-side, ensuring your code remains private and secure.

How to Use the Online HTML Viewer

Testing your web code takes just three simple steps:

Write or Paste Code: Enter your HTML, CSS (in <style> tags), and JavaScript (in <script> tags) into the HTML Source editor on the left.
Watch the Preview: As you type, the Live Preview pane on the right automatically updates to show the result. No need to click "Run" or refresh pages.
Interact and Debug: Click buttons, test hover effects, and interact with your code in the preview pane just like a real website. Use "Open in New Tab" for a full-screen view.

Key Features of Our HTML Editor

We've designed this tool to be the perfect lightweight playground for web code:

Instant Live Preview: Zero-latency rendering updates your preview pane with every keystroke, perfect for fine-tuning CSS or layout adjustments.
Full Client-Side Execution: Your code runs directly in your browser's engine. It never touches our servers, guaranteeing 100% privacy and security for your projects.
Support for CSS & JavaScript: Don't just view static HTML. Include internal <style> and <script> blocks to test full component functionality and interactivity.
Isolated Sandbox: The preview runs in a sandboxed iframe, ensuring that your test code doesn't conflict with the tool's interface or pose security risks.
Responsive Testing: Because the preview pane is resizable (by resizing your browser window or using browser dev tools), you can easily test responsiveness.

Who Needs an Online HTML Viewer?

This tool serves a wide range of use cases in the web development ecosystem:

Web Developers

Quickly prototype UI components, debug messy HTML snippets, or test CSS flexbox/grid layouts in isolation before integrating them into a larger project codebase.

Students & Educators

The best way to learn HTML is by doing. Students can type tags and immediately see what they do, reinforcing concepts like block vs. inline elements, box models, and dominance hierarchies.

Email Marketers

Test HTML email templates to ensure tables and inline styles render correctly before loading them into your campaign manager.

CMS Content Editors

Verify HTML snippets intended for WordPress widgets, Shopify liquid files, or other CMS platforms to ensure they don't break your site layout.

Understanding the Basics: HTML, CSS, and JS

Our viewer supports the three core technologies of the web together:

HTML (Structure)

HyperText Markup Language provides the skeleton. Use tags like <h1>, <div>, and <span> to structure content. Our viewer renders semantic HTML5 correctly.

CSS (Presentation)

Cascading Style Sheets control the look. Add a <style> block in your HTML to define colors, fonts, and layouts. The live preview is perfect for tweaking values like `margin`, `padding`, and `box-shadow`.

JavaScript (Behavior)

JS adds interactivity. Include a <script> block to add logic, event listeners (clicks, inputs), and dynamic content updates. Our sandbox allows standard JS execution for testing logic.

Best Practices for Using the Playground

Use Internal Styles: Since you're working in a single file environment, place CSS in <style> tags in the <head> or body.
External Resources: You can link to external libraries (like Bootstrap, Tailwind via CDN, or FontAwesome) using <link> or <script> tags to test frameworks.
Console Debugging: If writing JavaScript, use your browser's Developer Tools (F12) Console to see `console.log()` outputs from the preview iframe.

Frequently Asked Questions

Is my code saved on your server?

No. The HTML Viewer works entirely in your browser (client-side). Your code is never sent to or stored on our servers, ensuring complete data privacy.

Can I use external CSS or JavaScript libraries?

Yes! You can include external resources like Bootstrap, jQuery, or Tailwind CSS by adding the appropriate CDN links (<link> or <script src="...">) in your code.

Why isn't my JavaScript running?

Ensure your JS is inside <script> tags. Also, check your browser console (F12) for syntax errors. The sandbox allows scripts, but some restrictively blocked browser APIs might not work.

Can I test responsive designs?

Yes. The simplest way is to resize your browser window. The preview pane behaves like a responsive viewport, adjusting content based on the available width.

Does it support HTML5 and ES6+ features?

Yes, the viewer supports whatever features your current web browser supports. If you are using a modern browser (Chrome, Edge, Firefox), you can use the latest HTML5 tags and Modern JavaScript features.

How do I view the result in full screen?

Click the "External Link" icon in the Live Preview pane header. This opens a new tab containing only your rendered code, free from the editor interface.

Can I render local images?

Due to browser security restrictions, you cannot directly link to files on your hard drive (e.g., `C:/images/pic.jpg`). Use online image URLs (like placeholder.com) or Base64 encoded images instead.

Is there a limit to code size?

Practically, no. You can paste thousands of lines of code. However, extremely large/complex scripts might slow down the real-time rendering on slower devices.