RunJS LogoRunJS

The JavaScript playground
for your desktop

Diamond
isAnagram
Node
const limit = 15;
let count = 1;
Array(limit).fill(0).reduce((acc, _, index) => {
const spaces = ' '.repeat(
Math.abs(limit - count) / 2
);
Other platforms

Explore and experiment with JavaScript and TypeScript, visualise your ideas and get instant feedback as you type.

Platforms

Latest version: 2.7.3

macOS (.app)Universal
Windows (.exe)64 bit
Linux (.deb)64 bitARMARM 64
Linux (.tar.gz)64 bitARMARM 64

Features

Exploring JavaScript has never been easier. Live feedback as you type, with per-line results makes it super clear what your code is doing.

Quirky
Web Audio
Server
Fetch

With RunJS you have access to Node and Browser APIs, including full DOM access. This gives you a level of versatility that's not possible in a standard REPL or Chrome console.

Babel and TypeScript support enables you to write modern, up-to-date syntax.

TypeScript
Babel

Use RunJS for free
or purchase a license to unlock powerful features and functionality.

NPM Packages

Experiment with new libraries and frameworks

NPM Packages

Multiple Tabs

Essential for multi-tasking

Multiple Tabs

Autocomplete

See code suggestions while you type

Autocomplete

Snippets

Create your own snippet collection

Snippets

Type Checking

See type related errors and warnings

Type Checking

Hover Info

Quickly see type information and relevant documentation

Hover Info

Environment Variables

Easily store important data and access it in your code

Environment Variables

Extra Themes

Ayu, One Dark, Shades of Purple, SynthWave '84

Extra Themes

Loved by developers all over the world

Awesome JS playground here. Its similar to Swift playgrounds - every line of JS code will be evaluated separately, with output printed on the right. Great tool for exploring JS!
Stephen Grider

Stephen Grider

RunJS - a desktop app that serves as a JavaScript scratchpad. This is one of my favorite tools for debugging and testing things quickly.
Joe Previte

Joe Previte

If you want to know what a piece of JS code will do, there's no substitute for just RUNning it and seeing the result! RunJS has become an essential tool in my daily JS development, writing, and teaching work, unseating a bunch of other tools like consoles, CLIs, and in-browser code editors.
Kyle Simpson

Kyle Simpson

This. is. awesome: RunJS, a JavaScript playground for Mac. Supports TypeScript, Babel transpilation, Node and browser APIs altogether, import Node modules from a folder, and more.
Flavio Copes

Flavio Copes

Was looking for a simple Javascript REPL Mac app and ran across RunJS.. this is perfect. simple little sandbox to tinker with JS before writing it for real in my main environment.
Paul Stamatiou

Paul Stamatiou

I teach code school and mentor junior engineers at work. When there’s a question about the language, it is so easy to just throw RunJS up on the screen and run little experiments in a safe and clear environment until everybody’s got the behavioural info they need to make a choice.
Al Zimmerman

Al Zimmerman

So grateful to have discovered RunJS. It's so much easier to practice JavaScript when you can see the solution in real time!
Cassandra Rossall

Cassandra Rossall

RunJS icon

Go on, give it a try.