JS Shell

Paste HTML in. Tap run. See your page on a real localhost — secure context and all. Camera, mic, fetch, WebRTC: everything Just Works. No Xcode required.

JS Shell is a pocket-sized developer console that lets you write, run, and test web code (HTML, CSS, JavaScript) directly on iOS and macOS. No Xcode, no laptop, no remote server.

Paste a page in, tap run, and it loads in a real WKWebView served from a local HTTP origin.

A real secure-context origin on iOS, so modern web APIs — from WebRTC to Geolocation — behave the way they should.

KEY FEATURES

Local HTTP server. An in-process server bound to the loopback interface. Provides a real secure-context origin so modern Web APIs work out of the box. Not reachable from outside the device.

JavaScript REPL. A full JavaScript runtime backed by JavaScriptCore. Type js to enter the REPL. console.log, fetch, setTimeout, setInterval, Promises, and async await are all available. Real Promises, real microtasks, real JSON parsing, real URL parsing.

Geolocation support. Test navigator.geolocation on a real iOS device. Permissions are handled by the system, just like Safari. Useful for validating location-based web features without deploying to a server.

Persistent file system. Files you paste live in your Documents directory and survive app restarts. Each downloaded package gets its own directory. iCloud backup picks them up like any other app data.

SQLite key-value store. A real B-tree on disk via SQLite. Read and write from your pages with same-origin fetch. No CORS configuration required.

curl. A subset of curl built on URLSession. The flags X, H, d, i, I, o, A, m, v are supported. Pretty-prints JSON responses and saves binary blobs to the virtual filesystem.

Archive extraction. In-process tar, tar.gz, tgz, gz, and zip extraction. No shelling out. Download a release tarball with curl, extract it, and run it immediately.

Voice commands. Tap the mic, speak a command. Apple Speech framework converts speech to text. Auto-submits on detected silence. Voice commands are saved to the scripts list for one-tap re-run.

Saved scripts. Save any sequence of commands as a named script. One-tap to re-run later. Voice-recognized commands are auto-saved to the scripts list for instant replay.

Mac Catalyst support. Runs natively on macOS as a Mac Catalyst app. Multi-window, resizable, fullscreen-capable. The same code that runs on your iPhone runs on your Mac.

DESIGNED FOR DEVELOPERS

JS Shell is a tool for people who want to test web code on a real iOS device without installing Xcode, syncing files, or setting up a tunnel. It is especially useful for:

Testing geolocation, camera, and microphone permission flows on iOS.

Validating fetch, CORS, and cookie behavior on a real iPhone. Building small offline web tools that need persistent state. Running JavaScript snippets without opening Safari Inspector. Debugging mobile rendering edge cases on the device itself.

PRIVACY

JS Shell does not collect any user data. There is no telemetry, no ads, no analytics, no third-party SDKs, no remote configuration. Everything you type, paste, or download stays on your device. The local HTTP server only listens on the loopback interface and is not reachable from any network.

The app forwards camera, microphone, speech recognition, and location permissions to web pages you load, exactly like Safari does on macOS. The first time a page tries to use them, iOS shows the standard system permission prompt. The first time a page tries to use them, iOS shows the standard system permission prompt.