Take your pick:

Home Assistant is a popular open-source home automation platform that allows users to control and monitor their smart devices. It prioritizes user privacy and offers a wide range of integrations.

ioBroker is an open-source IoT platform that enables users to connect and control various smart devices. It supports a wide range of protocols and offers a customizable interface.

Domoticz is a lightweight home automation system that supports various devices and protocols. It offers a user-friendly interface and can be run on low-power devices like Raspberry Pi.

FHEM is a flexible, open-source home automation server that supports a wide range of devices and protocols. It is highly customizable and can be controlled via a web interface or command-line interface.

Node-RED is a flow-based programming tool for wiring together hardware devices, APIs, and online services. It can be used to create custom home automation solutions and offers a wide range of integrations.

Jeedom is an open-source home automation platform that supports various devices and protocols. It offers a customizable interface and can be controlled via a web interface or mobile app.

Calaos is a complete home automation solution that includes a server application, a touchscreen interface, and mobile apps for iOS and Android. It supports various devices and protocols.

Pimatic is a home automation framework for Node.js that supports various devices and plugins. It offers a web-based interface and a RESTful API for controlling devices.