Arduino IDE

https://www.arduino.cc/en/Main/Software

Everybody's favorite when starting to work in the Internet of Things domain seems to be the Arduino-IDE. There is such a huge repository of ready-made software projects that can easily be installed and customized with this IDE makes it the natural choice for lots of hobby projects. However, when deploying multiple nodes of a systems and connecting a huge number of devices, the maintenance of a swarm of devices becomes cumbersome. We suggest, also taking a look at ulnoiot, node-red, PlatformIO and/or Mongoose OS at the point you encounter these requirements.