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Code Playground

Processed Client Side

Write HTML, CSS, and JavaScript in a VS Code editor and run it live in your browser — with console output and error reporting. Nothing is uploaded.

Editor
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Preview
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Console
console.log() output and runtime errors appear here.

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About Code Playground

This tool runs entirely in your browser. Whatever you paste is processed on your own device and is never uploaded, logged, or sent to any server.

The Code Playground is an in-browser code editor and sandbox for writing HTML, CSS, and JavaScript and running it instantly. It uses Monaco — the same editor that powers Visual Studio Code — so you get real syntax highlighting, autocomplete, bracket matching, and familiar keyboard shortcuts, paired with a live preview and a console that captures your logs and runtime errors. Reach for it to prototype a UI snippet, test a piece of JavaScript, reproduce a bug, or teach and learn front-end code without setting up a local project.

Key features

  • Monaco editor — the VS Code editor engine — with syntax highlighting, IntelliSense autocomplete, and VS Code keybindings
  • Separate HTML, CSS, and JavaScript tabs that are combined into a single live document
  • Live preview that re-runs automatically as you type, with a debounce so it updates smoothly
  • Auto-run toggle — switch it off to edit freely and run on demand with the Run button
  • Built-in console that captures console.log, info, warn, and error with colour-coded levels
  • Runtime error reporting — uncaught exceptions and unhandled promise rejections are shown in the console, not swallowed
  • Your code runs in a sandboxed iframe, isolated from the rest of the page
  • Reset button to restore the starter template, and a one-click console clear
  • Runs entirely in your browser — your code is never uploaded, logged, or sent to any server

How to use it

  1. Write your markup in the HTML tab — you only need the elements inside the body, no boilerplate required.
  2. Switch to the CSS tab to style it, and the JS tab to add behaviour; the three are merged into one page automatically.
  3. Watch the Preview pane on the right update live as you type — no build step, no save.
  4. Use console.log() in your JavaScript and read the output in the Console panel below the preview.
  5. If something throws, the error appears in red in the console and the status badge shows the error count.
  6. Turn off Auto-run if you prefer to edit a lot before executing, then click Run when you are ready.

Tips & common mistakes

  • You do not need <html>, <head>, or <body> tags in the HTML tab — write just the content and the playground wraps it for you.
  • The console captures objects too: console.log(myObject) prints a readable JSON view, so you can inspect state without a debugger.
  • A runtime error stops the rest of that run, exactly like a real page — fix the reported line and the preview re-runs automatically.
  • Because each run reloads the sandboxed iframe, there is no leftover state between runs; refresh-style bugs surface immediately.
  • This is a front-end (HTML/CSS/JS) sandbox — it does not run Node.js, npm packages, or server-side languages like Python or PHP.
  • Nothing you type is uploaded, so it is safe to paste proprietary snippets or reproduce a bug from private code.

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Frequently asked questions

8

It is a free online code editor and sandbox for writing HTML, CSS, and JavaScript and running it instantly in your browser. It uses Monaco, the editor that powers Visual Studio Code, so you get real syntax highlighting and autocomplete, plus a live preview and a console — with no sign-up and nothing to install.

It uses Monaco, the same editor engine that VS Code is built on, so the editing experience — syntax highlighting, IntelliSense, and keybindings — matches VS Code. It is not the full VS Code application with extensions and an integrated terminal, because that requires a backend server; this is a focused, client-side editor and runner for web code.

Yes. Write JavaScript in the JS tab and it runs live against your HTML and CSS in the preview. Use console.log() and the output appears in the Console panel below the preview, with warnings and errors colour-coded so you can debug as you go.

Yes. Uncaught exceptions and unhandled promise rejections are captured and shown in red in the console, along with the message, and the status badge shows how many errors the last run produced. This makes it useful for reproducing and fixing a bug, not just running working code.

No. The playground is a front-end sandbox that runs HTML, CSS, and browser JavaScript only. It does not execute Node.js, install npm packages, or run server-side languages like Python, PHP, or Java, because everything runs locally in your browser with no server.

No. In the HTML tab you only write the content that goes inside the body — the playground automatically wraps it in a full document and injects your CSS and JavaScript. You are free to add a full document if you prefer, but it is not required.

Everything runs entirely in your browser. Your code is never uploaded, logged, or sent to any server, and it executes in a sandboxed iframe isolated from the rest of the page, so it is safe to paste proprietary or private code.

Turn off the Auto-run toggle in the preview toolbar. With auto-run off, you can edit as much as you like and then click the Run button to execute your code on demand.