ClipCross

A lightweight LAN shared clipboard between a Windows PC and an Android phone — a small, fast alternative to Windows Phone Link for copying text, images and files between devices.

• PC: Go system-tray app. Single ~11 MB .exe, no runtime to install.
• Android: native Kotlin app. ~6 MB APK.
• Transport: one TLS port on the LAN carrying a WebSocket control channel + HTTPS file transfer. The phone finds the PC via mDNS; pairing is a QR scan.
• No cloud. Everything stays on your local network.

Status — feature complete (v1)

All phases built and verified on Android 14:

Feature	phone → PC	PC → phone
Text clipboard	Share sheet / tile / button	Auto (tap-to-copy notification)
Image clipboard	Share sheet	Auto (inline / HTTPS)
File transfer	Share sheet → HTTPS	Tray "Send file…" → HTTPS, saved to Downloads/ClipCross
Open link on other device	Share → "Open link on PC"	Tray "Open clipboard link on phone"
Clipboard history (last 20)	Phone history screen	Tray "Recent" submenu
Run at login	—	Tray "Start with Windows"

Footprint: PC idle working set ≈ 22 MB (vs Phone Link's hundreds of MB across processes); windowless stripped exe ≈ 8 MB. Android APK ≈ 6 MB.

Sync model

Hybrid, chosen to fit Android's clipboard rules (Android 10+ blocks background clipboard access):

• PC → phone: automatic. Sets the clipboard when the app is foreground; else posts a "tap to copy" notification.
• phone → PC: manual push via the Android Share Sheet, a Quick Settings tile, or an in-app button (content arrives through the share intent, so no restricted clipboard read is needed).

Build & run

PC (Go 1.26+)

cd pc
# dev build (keeps a console for logs)
go build -o clipcross.exe .
# release build (no console window, smaller binary)
go build -ldflags "-H=windowsgui -s -w" -o clipcross.exe .
./clipcross.exe

A tray icon appears. Config, TLS cert, pairing QR, clipboard history and the log (clipcross.log) live in %APPDATA%\ClipCross. Use the tray's Start with Windows to launch it at login.

Android (JDK 17+, Android SDK)

cd android
./gradlew.bat :app:assembleDebug

APK: android/app/build/outputs/apk/debug/app-debug.apk.

Install on the phone (USB debugging enabled, phone plugged in):

& "$env:ANDROID_HOME\platform-tools\adb.exe" install -r app\build\outputs\apk\debug\app-debug.apk

Or copy the APK to the phone and install it manually (allow "install unknown apps").

Pairing

1. Make sure the PC and phone are on the same Wi-Fi / LAN.
2. PC tray → Pair device… → a QR image opens.
3. Phone app → Pair with PC → scan the QR.
4. The phone stores the host, port, auth token and the PC certificate fingerprint (pinned, trust-on-first-use), then connects. The tray status shows "1 phone connected".

Layout

pc/                 Go system-tray app
  internal/config     settings (%APPDATA%\ClipCross\config.json)
  internal/tlsutil    self-signed cert + fingerprint
  internal/server     WebSocket + HTTPS file endpoints
  internal/discovery  mDNS advertising
  internal/pairing    pairing payload + QR
  internal/tray       tray icon/menu
android/            Kotlin app
  .../data            SharedPreferences pairing store
  .../net             OkHttp WS client, cert pinning, mDNS, messages
  .../service         foreground service (connection + reconnect)
  .../ui              main screen + QR pairing