Install JSLab

System requirements

JSLab runs on Apple Silicon Macs only, on macOS 14 or later. It needs macOS 14 because license verification uses WebKit’s Ed25519 support, which macOS 13 lacks.

Download

Download JSLab from js-lab.app, open the .dmg and drag JSLab into your Applications folder.

JSLab runs as a 14-day free trial until you enter the license key from your purchase email. The trial needs no account and no card.

Open JSLab the first time

Open JSLab from Applications or Launchpad.

What you see first

If you open JSLab straight from the disk image, it first offers to move itself into Applications.

The first launch plays a short intro: the JSLab logo draws itself, opens into the editor and output, and becomes the Welcome tab line by line, with a chime (turn it off with Intro Sound in Settings → Appearance). Press Esc to skip it. With Motion set to Reduced, the intro fades instead.

The Welcome tab is a live TypeScript sample on the Browser & Node APIs runtime, with the Web View and Tailwind on. It shows Auto Log, a magic comment, logpoints, Node’s built-in modules, a fetch with no CORS in the way, and a small counter card in the page. Edit anything and it runs again. Help → Replay Intro plays the intro again in a new tab, and Learn JSLab — also Help → Learning & Tips in the app — walks through every feature.

Every later launch restores your previous session instead. Continue with Your first tab.

Install the jslab command

JSLab also ships a jslab command for opening files and piped code from a terminal. Choose Help → Install jslab Command… to add it. See The jslab CLI.