💻

Developer Playground

HTML/CSS/JS sandbox, JSON formatter, Regex tester, Base64 encoder, and more. Everything runs in your browser.

Ctrl+Enter to run

<h1 style="color:#38bdf8">Hello World!</h1>
<p>Edit this HTML and press Run ▶</p>
<button onclick="greet()">Click me</button>

body {
  font-family: system-ui, sans-serif;
  background: #0f172a;
  color: #e5e7eb;
  padding: 20px;
}
h1 { margin: 0 0 12px }
button {
  background: #38bdf8;
  border: none;
  border-radius: 8px;
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
  color: #020617;
  font-weight: 700;
}

function greet() {
  document.querySelector('h1').textContent = 'You clicked! 🎉';
  document.querySelector('h1').style.color = '#86efac';
}