Frontend Mastery.
Near-Instant.
Near-Instant.
Near-Instant.
A fast, free HTML sandbox in your browser. Write HTML, CSS, & JavaScript, see changes instantly with hot module replacement, and export in one click. Your code runs only in your browser.
A Complete Browser Sandbox for HTML, CSS, and JS.
No build steps. No Webpack. Just write pure frontend code and watch the DOM update instantly. Perfect for prototyping, testing CSS layouts, and debugging JavaScript logic.
Near-Instant Live Preview
Test your HTML layouts and CSS animations in real-time. Our client-side engine injects DOM updates instantly without a full page refresh.
<div class="hero">
<h1>Hello World</h1>
</div>
Vanilla JS Execution
Run complex ES6+ JavaScript directly in your browser's memory. Inspect outputs using our integrated developer console.
console.log('App loaded');
};
Import External CDNs
Need GSAP, jQuery, or Three.js? Inject any library via unpkg instantly using our built-in dependency manager.
⚡ GSAP Ready.
Full Workspace. $0.
Other cloud web IDEs charge you monthly just to keep your frontend projects private. We built a free, local code editor for the community.
Free Forever — The Only Plan
Every built-in feature free. No card required.
How It Works
From blank tab to running page in four steps.
Step 1 — Open the workspace
One click and you're in — the workspace opens straight into a fresh project. A fresh project with index.html, style.css, and script.js is already waiting for you.
Step 2 — Write code
Type in the Monaco editor with Emmet abbreviations, autocomplete, and multi-cursor editing. It feels like VS Code because it runs the same engine.
Step 3 — Watch it update live
Every keystroke re-renders the preview through hot module replacement — no manual refresh, no build step standing between you and the result.
Step 4 — Debug and ship
Log to the integrated console, inject libraries from unpkg with a single command, then export your project as a ZIP when it's ready for the world.
Common Questions
Straight answers before you start typing.
Is it really free? What's the catch?
It's free with no catch hiding underneath: open the tab and code, with no trial timers and every built-in feature included. Your code lives in your browser's local storage, and the project itself is open source.
Where is my code saved?
In your browser's local storage on your own device — your code runs only in your browser and is never sent to NitroIDE. For safekeeping or moving between machines, export the project as a ZIP or push it to GitHub.
Can I use libraries like GSAP, Tailwind, or jQuery?
Yes. Open the developer console inside the workspace and inject any library from unpkg — type > install gsap and it's available to your page instantly, no package manager involved.
Does it work offline?
Yes. NitroIDE is an installable PWA: load it once, and the editor, preview, and your saved projects keep working without a connection.
How is this different from CodePen?
CodePen is built around single pens stored on their servers. NitroIDE gives you multi-file projects, a full VS Code-grade editor, local-first privacy with no account, and one-click export to a real, deployable project.
What is an HTML sandbox?
An HTML sandbox is a place to write, test, and preview HTML, CSS, and JavaScript right in your browser — no setup, no server, no account. NitroIDE is exactly that: type your code, watch the live preview update instantly, and export it as a ZIP when it is ready.