Sound Control - App-specific volume control
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
EarTrumpet - Volume Control for Windows
ioBroker - flexible and modular application for the IoT and Smarthome
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation