This HTML online compiler gives you three panes for HTML, CSS and JavaScript and a live preview beside them. It works like any online HTML editor, except that the HTML live preview rebuilds half a second after you stop typing, and a console underneath shows console.log output and uncaught errors from your script. Use this HTML, CSS and JS editor to prototype a layout, test a CSS rule, debug a snippet or put together a small demo to share, straight from your browser with nothing to install.
Paste the markup into the HTML pane and the rules into the CSS pane, then drag the divider next to the preview to watch the columns wrap.
<!-- HTML pane -->
<div class="grid">
<article>One</article>
<article>Two</article>
<article>Three</article>
</div>
/* CSS pane */
.grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
gap: 16px;
}
article {
padding: 24px;
border-radius: 8px;
background: #e0e7ff;
}
addEventListener keeps the handler in the JS pane, and each click also logs to the Console panel under the preview.
<!-- HTML pane -->
<button id="add">Clicked 0 times</button>
// JS pane
const button = document.getElementById('add');
let clicks = 0;
button.addEventListener('click', () => {
clicks += 1;
button.textContent = 'Clicked ' + clicks + ' times';
console.log('click', clicks);
});
CSS custom properties hold the colours, and toggling one class on the root element switches every value that uses them.
<!-- HTML pane -->
<main>
<h1>Theme demo</h1>
<button id="toggle">Toggle dark mode</button>
</main>
/* CSS pane */
:root { --bg: #ffffff; --fg: #111827; }
:root.dark { --bg: #111827; --fg: #f9fafb; }
body { background: var(--bg); color: var(--fg); }
// JS pane
document.getElementById('toggle').addEventListener('click', () => {
document.documentElement.classList.toggle('dark');
});
No. Browsers parse and render HTML and CSS directly, and they run JavaScript with a built-in engine that compiles it just in time, so there is no build step before a page works. Tools called an HTML compiler are really editors that render your code as you type, which is what the preview on this page does.
Yes. The editor, templates, console, import, export and share links are all free and need no account. Everything runs in your browser: the preview is built on your device and your code is saved to local storage rather than uploaded, so you can start working without signing up for anything.
The editor combines your HTML, CSS and JavaScript into one document and loads it into an iframe next to the panes. It rebuilds that document 500 milliseconds after you stop typing and clears the console each time. Click Run to force a full reload, for example to re-run code that only executes on page load.
Yes. The Library menu inserts a script or link tag for Tailwind CSS, Bootstrap 5 CSS, Font Awesome 6, Anime.js, Three.js or React 18 at the top of the HTML pane. You can also paste any other CDN tag yourself, because the preview loads external scripts and stylesheets like a normal web page does.
The JS pane is wrapped in a try block so that errors reach the console. That makes top-level let and const variables block-scoped instead of global, so inline attributes such as onclick cannot read them. Attach handlers with addEventListener in the JS pane, or assign the value to window, for example window.count = 0.
Your work auto-saves to this browser's local storage about a second after each change. To send it to someone, click Share for a link that encodes all three panes in the URL. To keep a file, click Export to download a single HTML page, and use Import to load an .html file back in.
Yes. The Templates menu has 10 starting points: Responsive Landing, Modern Form, Grid Gallery, Glassmorphism, Flexbox Center, Login Modal, Pricing Table, JS Todo List, Neumorphic Calc, Countdown. Loading one replaces the code in all three panes, and if you have already written something the editor asks you to confirm first, so you do not lose work by accident.
Paste this iframe into any web page and readers can run code without leaving it. The snippet travels in the URL, so there is nothing to host and no account to create. Open the sandbox, write your example, press Share, then append that link’s query string to the embed URL to preload it.
<iframe src="https://webfiddle.xyz/embed/html" width="100%" height="480" loading="lazy"
style="border:1px solid #ddd;border-radius:8px"
title="WebFiddle html sandbox"></iframe>