RunJS
The JavaScript playground for your desktop
Explore and experiment with JavaScript and TypeScript, visualise your ideas and get instant feedback as you type.
Platforms
Latest version: 2.1.1
Features
Explore JavaScript
Play with language features and get an immediate sense of how things work.
Try new libraries
Quickly and easily install packages from NPM. This is really useful for learning a new library or just experimenting with a familiar one.
See runtime values
Leave the Chrome console behind. RunJS shows you per-line results for your code as you type.
Use modern syntax
Babel and TypeScript support enables you to write the most up-to-date syntax.
Access Node and browser APIs
All the APIs that you're familiar with in Node and the browser are available in RunJS. This gives you a huge amount of functionality to explore.
Distraction free coding
Write code without distraction in a beautiful and simple interface. Choose from a great selection of themes and fonts to create an environment you're comfortable with.
Testimonials
Since the first release of RunJS in late 2018, many people from around the world and all kinds of backgrounds have said very kinds words about it.
Kyle Simpson
Software Engineer, Public Speaker, and Teacher in Austin, TX
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.
Stephen Grider
Engineering Architect and Instructor
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!
Joe Previte
Dev Advocate at Facebook Open Source
RunJS - a desktop app that serves as a JavaScript scratchpad. This is one of my favorite tools for debugging and testing things quickly.
Flavio Copes
Software Engineer, Writer of Tutorials
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
Paul Stamatiou
Designer
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.
Michael Uloth
Web Developer and Opera Singer
If you want to quickly see what a wee JavaScript snippet evaluates to, RunJS is a delightful way to find out. It's free. And pretty. And cross-platform. I dig it.
Cassandra Rossall
Aspiring Full-Stack Web Developer
So grateful to have discovered RunJS. It's so much easier to practice JavaScript when you can see the solution in real time!
Timo Laak
Software Developer
If you've never tried out RunJS before, give it a go! It's a JavaScript scratchpad which can also run your code. The best feature? It supports npm modules!
Kadu Magalhães
Software Development Student
A good tip for those who are studying JavaScript like me: RunJS! It's a playground that auto-evaluate your code as you type and you can also import libs and stuff
Shahryar Rajabpoor
Front-End Engineer
what a great tool! I've always had a problem with testing something in Javascript quickly, I always end up either in codesanbox, chrome devtools or my vscode to run a server to test ideas... but I found this today and I'm amazed by it!
Cyrus Zei
Full-Stack Developer
The more I use RunJS, the more I like it and wonder what I have been doing in the past when I wanted to test something in JS.
David Metcalf
Web Developer
Among my side hustles, I tutor coding bootcamp students via video chat. When screen sharing, RunJS has become my favorite way to isolate and explain bugs & expected behaviors. Awesome app, check it out!
Ujval Joshi
Developer and Designer
Really impressed with Javascript scratchpad tool RunJS. Useful while learning new concepts and trying it out.
Go on, give it a try.