Free Online JavaScript Playground
JavaScript Playground is an interactive coding environment that lets you write, run, and experiment with JavaScript directly in your browser. The workspace splits into three panels: a code editor on the left, a live rendered output in the top-right, and a console panel in the bottom-right. Every console.log, console.warn, console.error, and console.info call from your code is captured and displayed with color-coded badges. Six specialized sub-tools load curated code samples for different experimentation areas: general JavaScript, DOM manipulation, canvas drawing, animations, API calls, and algorithm benchmarks. Paste your code, upload a file from your computer, or drag and drop it onto the workspace. All processing happens locally in a sandboxed iframe, so your code never leaves your device.
JS Playground
Write and execute JavaScript with live DOM output and captured console messages in a split-pane workspace.
DOM Playground
Create elements, apply styles, and attach event listeners to build dynamic interfaces with JavaScript.
Canvas Playground
Draw shapes, text, and curves on an HTML5 canvas using the Canvas 2D API with instant visual feedback.
Animation Playground
Build smooth browser animations using requestAnimationFrame with a particle system sample to modify and learn from.
API Playground
Test fetch API calls with async/await, parse JSON responses, and render results dynamically in the live output.
Algorithm Playground
Benchmark sorting algorithms and compare performance using console output with sub-millisecond precision timing.
Online JavaScript Playground with Three-Panel Workspace
JavaScript Playground offers a unique three-panel layout that sets it apart from single-pane code runners. The code editor fills the left side of the workspace, while the right side splits vertically into a live output panel on top and a console panel below. Both panels update after each execution, so you see rendered DOM output and console messages simultaneously without switching tabs. A horizontal drag handle between the editor and output panels lets you resize the split, and a vertical drag handle adjusts the ratio between the live output and console. The status bar between the toolbar and workspace shows execution time, file size, and an auto-run toggle for live coding.
Six Specialized Sub-tools with Sample Code
Each sub-tool loads a curated code sample designed to demonstrate a specific JavaScript capability. Explore array methods and string templates in the JS Playground, or learn to build interactive cards using event listeners in the DOM Playground. The Canvas Playground allows for drawing complex shapes and curves with ease, while the Animation Playground showcases smooth motion with its particle system. Use the API Playground to practice fetching data from public REST endpoints, and compare sorting efficiency across various data sizes in the Algorithm Playground. Click Load Sample in the toolbar to reset to the default code for the active sub-tool at any time.
Upload JavaScript Files or Drag and Drop
Loading code into the workspace works three ways: paste directly into the editor, click Upload File in the toolbar to select a file from your computer, or drag and drop a file anywhere onto the workspace. Accepted formats include .js, .jsx, .ts, .tsx, .mjs, .cjs, .html, and .htm files. File reading uses the browser File API, so nothing is uploaded to any server and there are no file size restrictions.
Experiment with DOM, Canvas, Animations, and API Calls
The playground covers a full range of client-side JavaScript capabilities, from basic scripting to complex browser APIs. Control your web interface through DOM manipulation by creating elements, applying styles, and handling user interactions. The Canvas API provides pixel-level control for drawing custom shapes, gradients, and paths, while requestAnimationFrame loops deliver high-performance 60fps motion for games and UI effects. You can also integrate external data with the Fetch API sub-tool, which covers REST calls, JSON parsing, and error handling. Each area has a working sample that you can modify, extend, or replace entirely.
Benchmark Algorithms with Console Output
The Algorithm Playground switches to a full-height console view optimized for reading benchmark results. The default sample compares bubble sort, quick sort, and native Array.sort across array sizes of 100, 500, and 1000 elements. Performance.now() provides sub-millisecond timing for each run. Replace the sorting functions with your own algorithms to compare string operations, search functions, data structure traversals, or any computation you want to measure.
Auto-Run for Instant Feedback
Enable the auto-run toggle in the status bar and the playground re-executes your code 800 milliseconds after you stop typing. This transforms the workspace into a live coding environment where changes appear in the output and console as you type. For scripts that are slow or make network requests, keep auto-run disabled and click the green Run button when you are ready.
Free JavaScript Playground with Sandboxed Execution
Your code executes inside a sandboxed iframe with only the allow-scripts permission enabled. There is no same-origin access, no form submissions, and no access to the parent page DOM. Console methods are overridden to capture output through postMessage, but the original methods still work in your browser DevTools. Enjoy a completely private experience with no server requests, no cookies, and no account requirements. Close the browser tab and your code is gone.
Related JavaScript and Code Tools
If you work with JavaScript regularly, these tools complement what you can do in the playground:
- JavaScript Preview -- run JavaScript and HTML with live rendering, DOM inspection, code snapshots, and performance timing
- JS Beautifier -- format, beautify, minify, and validate JavaScript code
- JavaScript Compress -- compress and strip JavaScript for production
- JavaScript Obfuscator -- protect JavaScript with obfuscation
- JS Validator -- validate syntax, lint errors, and analyze code health
- JSON Formatter -- format, minify, validate, and transform JSON data
- HTML Formatter -- format and beautify HTML documents