If you want to create an IoT module as a commercial product and sell it, you will need to let the user configure the Wi-Fi credentials themselves as long as the MQTT server, port, username and password that will be used by user. All the extra information needs to be stored on the SPIFFS filesystem so when the module will start will be used to connect to Wi-Fi and to connect to the MQTT server.
In the first part of this chapter, we will discuss how to build a web server to get Wi-Fi network credentials with the help of the WiFiManager library, save them to the SPIFFS file, and in the second part, we will build a module that allows you to control a TV using infra-red.
By the end of this chapter, you will have gained the knowledge to start your first commercial IoT product.