HTML/CSS/JS Editor
Code, preview, and experiment with HTML, CSS, and JavaScript in real-time using our free online HTML-CSS-JS Editor. This interactive development environment lets you write code in three panels and see the rendered output instantly in a live preview pane. Perfect for prototyping web components, testing code snippets, learning web development, or sharing code examples. The editor features syntax highlighting for all three languages, auto-completion, error detection, responsive preview modes, and the ability to save and share your work via URL. No setup required — start coding immediately in your browser.
What Is
The HTML-CSS-JS Editor is an online integrated development environment (IDE) that combines three code editors with a live preview pane for rapid web development. It provides separate panels for HTML markup, CSS styles, and JavaScript code, with changes in any panel instantly reflected in the preview area. Key features include: syntax highlighting with language-specific color schemes, auto-indentation and bracket matching, responsive preview modes (desktop, tablet, mobile viewport sizes), console output capture for JavaScript debugging, support for popular libraries and frameworks via CDN links, local storage persistence so your code is saved between sessions, and URL sharing that encodes the entire project in the URL hash for easy collaboration. The editor uses contentEditable and iframe sandboxing to provide a secure, isolated preview environment.
How to Use
- Open the HTML-CSS-JS Editor in your browser — no installation or registration needed.
- Write your HTML code in the top panel — this defines the structure and content of your page.
- Add CSS styles in the middle panel to control the visual appearance and layout of your HTML elements.
- Write JavaScript in the bottom panel to add interactivity, dynamic behavior, and logic.
- The live preview pane updates instantly as you type — see your changes in real-time without refreshing.
- Use the share button to generate a URL with your code, or save your project for later editing.
Examples
Input: HTML: <h1>Hello</h1> + CSS: h1{color:red} + JS: alert(1)
Process: Combine 3 code panels → Sandbox in iframe → Live render output
Result: Live preview showing red 'Hello' heading
Input: Responsive test: viewport 375px vs 1024px
Process: Set iframe dimensions → Re-render at different breakpoints
Result: Side-by-side comparison of mobile vs desktop rendering
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Frequently Asked Questions
Is the HTML-CSS-JSS Editor free?
Yes, this tool is completely free to use with all features available immediately. There are no premium tiers, usage limits, or account requirements. You can create unlimited projects, use all editor features, and share your work without any restrictions.
Can I use external libraries and frameworks?
Yes, you can include any external CSS or JavaScript library via CDN links in your HTML. Popular frameworks like Bootstrap, Tailwind CSS, React, Vue, jQuery, and many others are supported. Simply add the CDN link in your HTML head section and use the library in your code.
Does it support preprocessors like Sass or TypeScript?
The editor provides syntax highlighting for Sass, SCSS, Less, TypeScript, and CoffeeScript, but does not compile them. For compiled languages, you would need to use the compiled output. The live preview runs standard HTML, CSS, and JavaScript only.
Is my code saved automatically?
Yes, your code is automatically saved to your browser's local storage as you type. When you return to the editor, your previous work will be restored. For permanent storage and sharing, use the share button to generate a URL containing your code.
Can I export my project?
You can copy the code from each panel to use in your own projects, or use the share URL to save a link to your work. The share URL encodes all three code panels in the URL hash, making it easy to bookmark or send to others. For full project export, copy the HTML, CSS, and JavaScript into separate files.
Does it work offline?
Once the page loads, the editor works fully offline. Code editing, preview rendering, and local storage all function without an internet connection. The only online features are CDN library loading and URL sharing, which require connectivity.