Download
Get SoundDrop
Pick your device. Updates arrive by themselves.
First launch
Installing
On Mac
Open the downloaded file and drag SoundDrop into Applications. The first time, macOS says it can't check the app: open System Settings → Privacy & Security and click Open Anyway.
On Windows
Unzip the folder and open SoundDrop. If Windows SmartScreen appears, click More info, then Run anyway.
On Linux
Unzip, open a terminal in the folder, and run ./SoundDrop.