English | 简体中文

One keyboard and mouse for several computers. ScreenFerry shares a keyboard and mouse between your computers, Mac or Windows in any combination, syncs the clipboard and sends files, all over TLS 1.3.

• Keyboard and mouse sharing: push the cursor off a screen edge to move to the next computer. Keys travel as physical keys, so keyboard layouts and input methods don't get in the way. Caps Lock stays in sync and media keys are forwarded.
• Many computers, either direction: any computer can be the controlling one, and one can control several, arranged on any side.
• Clipboard: plain text, formatted text and images, synced when the cursor moves over.
• Files: drag them to a screen edge to send. Interrupted transfers resume after reconnecting.
• Per-device settings: pointer speed (DPI), scroll direction and speed, modifier keys and key mappings, accidental-switch protection.
• Secure: confirm a 6-digit pairing code the first time, then only the paired certificate fingerprint is trusted.
• Easy to connect: automatic discovery on the local network. Where discovery is blocked, connect by address or invite from the controlling computer.
• Lightweight: a Rust background service in the tray. The settings window starts on demand and exits when closed.
• Automatic updates: checks once a day, downloads in the background, and installs when you choose Restart to Update. Every update is signature-checked first.
• English and Chinese: the settings window, tray menu and installer come in English and Simplified Chinese. They follow the system language, and you can switch in Settings → Appearance.

flowchart LR
  subgraph S["Controlling computer (keyboard and mouse)"]
    A["Background service<br/>captures input"]
    UA["Settings window"]
  end
  subgraph C["Controlled computer"]
    B["Background service<br/>injects input"]
    UB["Settings window"]
  end
  UA -.-|local IPC| A
  A ==>|"Input connection<br/>keys, mouse, switching"| B
  A <-->|"Data connection<br/>clipboard, files"| B
  B -.-|local IPC| UB

Each computer runs a background service that captures or injects input and handles networking and sync. The settings window is a separate process that talks to it over loopback. Each pair of devices keeps two TLS 1.3 connections, so a large file transfer never slows down the keyboard and mouse.

Trust is set up on the first connection:

sequenceDiagram
  participant C as Controlled
  participant S as Controlling
  S -->> C: mDNS announcement (or connect by address, or invite)
  C ->> S: TLS 1.3 handshake, both sides present device certificates
  opt First connection
    C ->> S: Pairing
    Note over C,S: Both sides show the same 6-digit code. Once confirmed, each remembers the other's certificate fingerprint
  end
  C ->> S: Open the input and data connections

ScreenFerry checks for updates once a day and downloads them in the background. Choose Restart to Update when it suits you; you can turn automatic checks off in Settings → About. Updates are verified against a built-in signing key before anything is installed.

About the Windows installer:

• It isn't code-signed. If SmartScreen blocks it, choose More info → Run anyway.
• It installs into Program Files and allows ScreenFerry through the firewall on private and domain networks.
• Updates install silently after one administrator prompt. While another computer controls this one, use this computer's own keyboard and mouse to approve it. Uninstall from Settings → Apps; your settings and pairings are kept.

1. Open ScreenFerry on both computers. By default a Mac controls and a Windows PC is controlled; change this in Settings → This Computer. When both computers run the same system, set the one without the keyboard and mouse to Be Controlled.
2. On the controlled computer, choose the controlling one on the Devices page and confirm the 6-digit pairing code on both sides. If it isn't found on the network, use Connect by Address, or Invite a Computer from the controlling one. The address is at the top of the other computer's Devices page.
3. On the controlling computer, arrange the screens on the Layout page, then push the cursor off a screen edge to move over.

If something goes wrong, export a diagnostics file from Log → Diagnostics and attach it when you report an issue. Device names, user names and file names are replaced with placeholders.

While the cursor is on another screen, press Ctrl+Option+Esc (Ctrl+Alt+Esc when Windows controls) to bring it back. Quit other keyboard and mouse sharing tools first so they don't compete for input.

See screenferry --help for all options. The command line and diagnostics log are in Chinese.

You need Rust (the version is pinned in rust-toolchain.toml and installed by rustup) and Flutter 3.47. macOS also needs Xcode; Windows also needs Visual Studio 2022 (Desktop development with C++) and Inno Setup 7.1 or later.

cargo xtask bundle

It builds for the system it runs on and puts the result in target/bundle/: ScreenFerry.app and its update package ScreenFerry-<version>-macos-<arch>.zip on macOS (add --dmg for the installer disk), ScreenFerry-<version>-windows-x64-setup.exe on Windows. Releases are made with cargo xtask release <version>; see ADR 0014. On macOS the app is signed with a Developer ID certificate from the keychain when there is one (or the one named by SCREENFERRY_SIGN_IDENTITY). Otherwise it gets an ad-hoc signature, and Accessibility permission has to be granted again after every rebuild.

flowchart TB
  app["Settings window · Flutter"] -.->|local IPC| L4
  subgraph L4["L4 Applications"]
    daemon["ferry-daemon → screenferry"]
  end
  subgraph L3["L3 Assembly"]
    engine["ferry-engine"]
  end
  subgraph L2["L2 Adapters"]
    direction LR
    pm["platform-macos"] ~~~ pw["platform-windows"] ~~~ net["net"] ~~~ store["store"] ~~~ ipc["ipc"]
  end
  subgraph L1["L1 Pure logic"]
    direction LR
    proto["proto"] ~~~ core["core"] ~~~ trust["trust"] ~~~ update["update"] ~~~ platform["platform (traits)"]
  end
  subgraph L0["L0 Domain types"]
    types["ferry-types"]
  end
  L4 --> L3 --> L2 --> L1 --> L0

Each layer depends only on lower layers. unsafe appears only in ferry-platform-*, and system-specific code only there and in the L4 applications.

cargo test --workspace
cargo xtask lint

Run flutter test in app/ for the settings window. The full pre-commit checklist is in AGENTS.md.

The engineering docs are written in Chinese:

Licensed under either MIT or Apache-2.0, at your option. Unless you state otherwise, any contribution you submit is licensed the same way.

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