Sill does one thing well: it takes a window from your Mac and puts it on your iPhone or iPad, live, with full input going back. Touch, trackpad, keyboard, Apple Pencil — all of it. The connection stays on your local network, a USB cable, peer-to-peer Wi-Fi, or your own VPN. There is no server. There is no account. There is no subscription. The technical spine is clean. Sill captures via ScreenCaptureKit, encodes HEVC on your Mac's hardware encoder via VideoToolbox, and ships it over TLS 1.3 directly to the iOS app. When bandwidth drops, it drops frames instead of queuing them — latency over fidelity, the right call for an input-driven tool. Input goes back the same encrypted pipe: taps, clicks, momentum scrolling, the on-screen trackpad, typed text, and Apple Pencil as pointer. Three-finger trackpad gestures map to Mission Control, App Exposé, and Spaces. The iPhone layouts are thoughtfully considered. Held upright, the window sits on top with controls below. Larger Picture mode gives the streamed window maximum screen real estate down to the keyboard line. On iPhone Duo (Apple's foldable), Sill follows the hinge — open flat for full display, half-open for picture-above-controls, closed for the cover display. The Aa feature resizes the Mac window itself so text is readable at your chosen size, then restores the original dimensions when you disconnect. Pairing is one-time per device: scan a QR code or type 12 digits, or just plug in a USB cable. Remote Access, off by default, lets paired devices reach your Mac through your own VPN or a forwarded port. The app automatically downgrades quality for remote sessions and restores home quality when you return to LAN. Clipboard sync carries text both ways, up to 256 KB, and respects password manager concealment flags. The privacy posture is genuine, not performative. No analytics, no tracking, no ads, no telemetry mentioned anywhere. The Mac app requires Screen Recording and Accessibility permissions — unavoidable for what it does — and captures nothing while no device is connected. The virtual display feature uses a private macOS API, which is why the Mac app ships from the developer's site rather than the Mac App Store. Sill is entirely free. The iOS app is on the App Store, the Mac app is a notarized download or a Homebrew cask install. You can build the iOS app from source in Xcode. The developer accepts tips through GitHub Sponsors but they unlock nothing. The codebase is Swift-only with zero third-party dependencies, and the CLAUDE.md contributing guide enforces latency-over-quality as a design principle. This is a solo developer shipping a polished, privacy-respecting tool that competes with commercial remote desktop apps, asking for nothing in return. The scope is intentionally limited — one window at a time, no audio, text-only clipboard — and those limits are stated plainly, not buried.
