Image: GitHub
Why it mattersA team paying for Duet Display or Astropad on every Mac to get an iPad second screen can test a server-less, open-source alternative that the publisher now installs through Homebrew and the App Store.
Paying for an iPad to act as a second screen has meant buying a product from Duet or Astropad. A new open-source project just released a free one that runs through the App Store on one side and Homebrew on the other.
Sill, published by Saffsanity under Apache 2.0, shows a window from a Mac live on an iPhone or iPad. The user controls it with touch, a trackpad, a keyboard or an Apple Pencil, and the two devices talk directly, with no account and no server in the middle. The repository has 2,455 stars 24 days after it was created, with 697 commits and a last-push on 15 October 2026.
What it does
Sill lives in the Mac menu bar. When a connected iPhone or iPad picks a window, or the whole desktop, Sill captures it with Apple's ScreenCaptureKit and encodes it as HEVC with VideoToolbox on the Mac's hardware video encoder. The picture flows over TLS 1.3 straight to the Sill app on the device, and the user's taps, scrolls and keys travel back the same way. The README says Sill captures nothing while no device is connected, and that when the encoder or the link falls behind it drops frames instead of queuing them to keep the picture current.
What it needs
The requirements section names Apple silicon on macOS 14 or later, and iOS 17 or iPadOS 17 or later on the device. The Mac asks for Screen Recording and Accessibility; on macOS 15 or later it also asks for Local Network. The device asks for Local Network, and for the camera when a user scans the pairing code on first setup. The two sides connect over the same local network, over a USB cable, over Direct Wireless Connection when no network is shared, or through a user's own VPN such as Tailscale.
Where it goes beyond basic screen-sharing
Three details stand out in the README. The clipboard travels both ways while a per-side Share Clipboard setting is on, and the publisher says Sill never reads the device's clipboard by itself and that items a password manager marks as concealed stay on the Mac. On iPhone Duo, the folding form factor, Sill follows the hinge: open flat gives the Mac picture the full inner display, half-open puts the picture above the fold with a trackpad and keys below. And the Mac's app menus reach the device, through the iPad's own menu bar on iPadOS 26 or later, and through a Menus button in Sill's bar otherwise.
How to install it
The README says Sill for Mac is a free notarised download from getsill.app, and that brew install --cask saffsanity/sill/sill installs the same download from Sill's own tap. Sill for iPhone and iPad is free on the App Store, and the repository holds the source for building the iOS client. The licence is Apache 2.0, which lets a team fork it and modify it without a licence call.
What it leaves open
Sill does not list a Windows or Linux Mac-receiver, so an iPad is the only remote screen. The README does not state a video latency figure, so a buyer who cares about pencil-input delay has to measure it on their own kit. The publisher is a single-name GitHub account rather than a company, and the privacy page lives on getsill.app beside the download. A team deciding whether to standardise on Sill reads those before swapping out a paid tool.
Source
- Saffsanity/sill on GitHub, Saffsanity
This item was written by an AI system from the linked source. Reveneau is responsible for what it publishes.
Get AI News in your inbox
New developer tools, model and agent releases, and how teams are actually using them to release software. Short, and only when there is something worth reading.
