Online HTML Compiler & Editor
Run HTML, CSS & JS Instantly in Your Browser

Free online HTML compiler and powerful online HTML editor. Write, edit, run and preview HTML, CSS, JavaScript code with real-time live preview — no installation, no setup required.

Launch Online HTML Editor →

`; }function runNow() { code[current] = editor.value; frame.srcdoc = buildDoc(); setStatus('Running…', false); setTimeout(() => setStatus('Ready', false), 800); }function refreshPreview() { runNow(); }// ── AUTO-RUN ── function toggleAutoRun() { autoRun = document.getElementById('autoRun').checked; document.getElementById('autoRunBadge').style.display = autoRun ? 'inline' : 'none'; }function handleTyping() { updateLineNums(); updateCursor(); updateCharCount(); if (autoRun) { clearTimeout(autoTimer); autoTimer = setTimeout(runNow, 900); } }// ── LINE NUMBERS ── function updateLineNums() { const lines = editor.value.split('\n').length; lineNums.textContent = Array.from({length: lines}, (_, i) => i + 1).join('\n'); }function syncScroll() { lineNums.scrollTop = editor.scrollTop; }// ── CURSOR ── function updateCursor() { const val = editor.value; const pos = editor.selectionStart; const before = val.substring(0, pos); const ln = before.split('\n').length; const col = before.split('\n').pop().length + 1; document.getElementById('cursorPos').textContent = `Ln ${ln}, Col ${col}`; }function updateCharCount() { document.getElementById('charCount').textContent = editor.value.length + ' chars'; }// ── TAB KEY ── function handleKey(e) { if (e.key === 'Tab') { e.preventDefault(); const start = editor.selectionStart; const end = editor.selectionEnd; const spaces = ' '.repeat(tabSize); editor.value = editor.value.substring(0, start) + spaces + editor.value.substring(end); editor.selectionStart = editor.selectionEnd = start + tabSize; handleTyping(); } }// ── FONT SIZE ── function setFontSize(px) { editor.style.fontSize = px + 'px'; lineNums.style.fontSize = px + 'px'; }// ── TAB SIZE ── function setTabSize(n) { tabSize = parseInt(n); editor.style.tabSize = n; }// ── THEME ── const themes = { dark: { bg: '#050505', text: '#d4d4d4', nums: '#333' }, mocha: { bg: '#1c1410', text: '#d5b998', nums: '#4a3828' }, midnight: { bg: '#0a0e1a', text: '#9eb4d6', nums: '#1e2a40' }, forest: { bg: '#0a140a', text: '#9dcea0', nums: '#1a2e1a' }, }; function setTheme(name) { const t = themes[name]; document.getElementById('editorPanel').style.background = t.bg; editor.style.color = t.text; lineNums.style.color = t.nums; lineNums.style.background = t.bg; }// ── FORMAT ── function formatCode() { // Basic indent normaliser for HTML/CSS/JS const val = editor.value; let out = '', depth = 0; val.split('\n').forEach(line => { const trimmed = line.trim(); if (!trimmed) { out += '\n'; return; } if (/^<\/|^\}/.test(trimmed)) depth = Math.max(0, depth - 1); out += ' '.repeat(depth * tabSize) + trimmed + '\n'; if (/<[^/!][^>]*[^/]>$/.test(trimmed) && !/^<(input|img|br|hr|meta|link)/.test(trimmed)) depth++; if (trimmed.endsWith('{')) depth++; }); editor.value = out.trimEnd(); handleTyping(); showToast('Code formatted'); }// ── COPY ── function copyCode() { navigator.clipboard.writeText(editor.value).then(() => showToast('Copied to clipboard')); }// ── DOWNLOAD ── function downloadCode() { code[current] = editor.value; const a = document.createElement('a'); a.href = 'data:text/html;charset=utf-8,' + encodeURIComponent(buildDoc()); a.download = 'project.html'; a.click(); showToast('Downloaded project.html'); }// ── RESET ── function resetEditor() { if (!confirm('Reset all code to defaults?')) return; code = { html: defaultCode.html, css: defaultCode.css, js: defaultCode.js }; editor.value = code[current]; updateLineNums(); updateCharCount(); frame.srcdoc = ''; showToast('Reset complete'); }// ── FULLSCREEN PREVIEW ── function fullscreenPreview() { code[current] = editor.value; const w = window.open('', '_blank'); w.document.write(buildDoc()); w.document.close(); }// ── STATUS ── function setStatus(msg, isError = false) { document.getElementById('statusMsg').textContent = msg; document.getElementById('statusDot').className = 'status-dot' + (isError ? ' error' : ''); }// ── TOAST ── function showToast(msg) { const t = document.getElementById('toast'); document.getElementById('toastMsg').textContent = msg; t.classList.add('show'); setTimeout(() => t.classList.remove('show'), 2500); }// ── DRAG RESIZE (Desktop) ── function startDrag(e) { isDragging = true; dragStartX = e.clientX; dragStartW = document.getElementById('editorPanel').offsetWidth; document.getElementById('divider').classList.add('dragging'); document.body.style.userSelect = 'none'; document.addEventListener('mousemove', onDrag); document.addEventListener('mouseup', stopDrag); } function onDrag(e) { if (!isDragging) return; const total = document.getElementById('editorArea').offsetWidth; const newW = Math.max(200, Math.min(total - 200, dragStartW + (e.clientX - dragStartX))); document.getElementById('editorPanel').style.width = newW + 'px'; document.getElementById('editorPanel').style.flex = 'none'; } function stopDrag() { isDragging = false; document.getElementById('divider').classList.remove('dragging'); document.body.style.userSelect = ''; document.removeEventListener('mousemove', onDrag); document.removeEventListener('mouseup', stopDrag); }// ── DRAG RESIZE (Touch/Mobile vertical) ── function startDragTouch(e) { const touch = e.touches[0]; dragStartY = touch.clientY; dragStartW = document.getElementById('editorPanel').offsetHeight; document.addEventListener('touchmove', onDragTouch, { passive: false }); document.addEventListener('touchend', stopDragTouch); } function onDragTouch(e) { e.preventDefault(); const touch = e.touches[0]; const delta = touch.clientY - dragStartY; const newH = Math.max(120, dragStartW + delta); const ep = document.getElementById('editorPanel'); ep.style.height = newH + 'px'; ep.style.flex = 'none'; } function stopDragTouch() { document.removeEventListener('touchmove', onDragTouch); document.removeEventListener('touchend', stopDragTouch); }

What is an Online HTML, CSS & JS Compiler?

An online HTML, CSS & JS compiler is a browser-based web development tool that lets you write, edit, compile and run HTML, CSS, and JavaScript code instantly with live preview. Our online HTML editor requires no installation and works in any browser — ideal for learning, testing snippets, and front-end prototyping.

How Our Online HTML Compiler Works

1

Write Your Code

Use tabs in our online HTML editor for HTML, CSS & JavaScript.

2

Click Run

See instant live preview with real-time code execution.

3

Edit, Test & Download

Refine instantly, test responsively, download files.

HTML Basics & Examples – Learn in Our Online HTML Editor

About HTML

HTML (HyperText Markup Language) is the standard markup language for web pages. Created by Tim Berners-Lee in 1991, almost every website uses HTML as its foundation.

HTML Fundamentals & Syntax

• Every document must start with <!DOCTYPE html>
• Root element: <html> … </html>
• Headings: <h1> to <h6>
• Paragraphs: <p>…</p>
• Links: <a href="…" title="…">…</a>
• Images: <img src="…" alt="…" />
• Buttons: <button>…</button>
• Lists: <ul> (unordered), <ol> (ordered), items in <li>

Example link:

<a href="https://example.com">Try Our HTML Code Compiler</a>

HTML Elements and Attributes

An element consists of opening tag, content, closing tag. Attributes add information (e.g. href, src, alt).

Example:

<img src="logo.png" alt="Online HTML Editor Logo" width="200">

CSS Basics

CSS controls appearance — colors, fonts, spacing, layout.

Example:

h1 {
  color: #2dd4bf;
  font-size: 2.5rem;
  text-align: center;
  margin-bottom: 1.5rem;
}
button {
  background: #2dd4bf;
  color: black;
  padding: 0.75rem 1.5rem;
  border-radius: 9999px;
}

HTML Tables

Tables use <table>, rows <tr>, headers <th>, cells <td>.

<table border="1">
  <tr>
    <th>Name</th>
    <th>Tool</th>
  </tr>
  <tr>
    <td>Best for beginners</td>
    <td>Online HTML Editor</td>
  </tr>
</table>

HTML + JavaScript

Add interactivity using <script> tags (inline or external).

Inline example:

<button onclick="alert('Hello from our html css js online compiler!')">Click Me</button>

External example:

<script src="script.js"></script>

Features of Our HTML Compiler Online & Editor

Real-Time Preview

Instant live code execution — changes appear immediately.

No Installation Needed

Use this online HTML editor in any browser, any device.

HTML + CSS + JS Support

Full html css js online compiler capabilities.

Mobile Responsive Testing

Preview how your design looks on phones/tablets.

One-Click Download

Export complete project as HTML file.

Free & Unlimited

No limits, no sign-up for our html compiler online.

Online HTML Compiler vs Traditional IDE

Feature	Our Online HTML Compiler	Traditional IDE
Installation Required	No	Yes
Runs in Browser	Yes	No
Instant Live Preview	Yes	Limited
Works on All Devices	Yes	Mostly Desktop

A detailed visual comparison highlighting key differences between an HTML compiler and an IDE, including performance, features, usability, and development capabilities.

Who Uses Our Online HTML Editor?

Beginners & Students

Learn HTML basics with instant feedback.

Developers

Quickly test snippets and prototypes.

Front-End Prototyping

Build and debug responsive designs fast.

Coding Interviews

Practice without local setup.

What Developers Say About Our Online HTML Compiler

★★★★★

“The best free online HTML editor I’ve used. Instant preview, clean UI, and no distractions. Perfect for quick frontend testing.”

Ayesha Khan

Front-End Developer

★★★★★

“I use this HTML CSS JS online compiler daily for snippet testing. It’s faster than opening my IDE.”

Michael Carter

Full Stack Engineer

★★★★★

“As a beginner, this online HTML compiler helped me learn faster with real-time feedback. No installation headaches.”

Daniel Rodriguez

Computer Science Student

❮ ❯

Best Online HTML CSS Compiler for Beginners

Our free online HTML editor offers simple tabs, real-time preview and helpful examples — perfect for learning without complexity.

Free HTML CSS JS Online Compiler with Live Preview

Enjoy full html css js online compiler features at zero cost — instant execution and mobile-friendly preview.

How to Run HTML Code Online Without Installing Anything

Just open our online HTML compiler, write or paste code, click Run — everything happens in your browser.

Frequently Asked Questions

Is this online HTML compiler free? +

Yes — 100% free with unlimited usage. No sign-up, no limits on our online HTML editor & compiler.

Can I use HTML, CSS and JavaScript together? +

Yes — dedicated tabs for each. Our html css js online compiler combines them seamlessly with live preview.

Does this online HTML editor work on mobile? +

Yes — fully responsive. Code and preview on phones/tablets using any modern browser.

How is this different from VS Code or other IDEs? +

No installation or heavy software — our online HTML compiler runs instantly in-browser for fast testing and learning.

Can I download the code I write? +

Yes — one-click download of a complete HTML file with embedded CSS and JS.

Start Using the Best Online HTML CSS JS Compiler & Editor

• Free online HTML compiler — no registration
• Real-time preview for HTML, CSS, JavaScript
• Browser-based — works on any device
• Great for beginners, students, developers & quick tests
• Includes HTML basics examples to help you learn

Fast, free, no-install online HTML editor and compiler — perfect for front-end development, learning and prototyping.

Open HTML Code Compiler Now →

';previewEl.srcdoc = finalContent; }function resetEditor() { if (confirm("Reset all code?")) location.reload(); }function downloadCode() { const h = compilerStore.active === 'html' ? editorEl.value : compilerStore.html; const c = compilerStore.active === 'css' ? editorEl.value : compilerStore.css; const j = compilerStore.active === 'js' ? editorEl.value : compilerStore.js;const out = '' + '' + '' + '' + '' + '' + '';const blob = new Blob([out], { type: 'text/html' }); const url = URL.createObjectURL(blob); const a = document.createElement('a'); a.href = url; a.download = 'my-project.html'; a.click(); URL.revokeObjectURL(url); }window.onload = () => { editorEl.value = compilerStore.html; compile(); };