Home Assistant is a free and open-source home automation software designed to be the central control system in a smart home or smart house. Written in Python, it focuses on local control and privacy. All data is on your own home assistant system, which is ideally a Raspberry Pi or a minicomputer.
Home Assistant has a very wide support of devices and offers over 2200 plugins with system integrations to various IoT technologies, systems and services. Here is the list of supported systems. home-assistant.io/integrations
The Home Assistant project started in September 2013. In November 2013, the core functionality was first published on GitHub. As of May 2020, there were more than 1,930 developers contributing to the core of the project. Here you can find the homepage of the project. https://www.home-assistant.io/
The great advantage of this system is that any connected device can be used for control.
The temperature value of the inexpensive Bluetooth thermometer can be used as an outside sensor to control the central heating. I can control my thermostats from two different manufacturers together and don’t have to work with two apps on my cell phone.