There are many so-called 'Arduino compatible' platforms on the market. The ESP8266 - in the form of the WeMos D1 Mini Pro - is one that really stands out. This device includes WiFi Internet access and the option of a flash file system using up to 16 MB of external flash memory. Furthermore, there are ample in/output pins (though only one analogue input), PWM, I²C, and one-wire. Needless to say, you are easily able to construct many small IoT devices!This book contains the following builds:A colourful smart home accessoryrefrigerator controller230 V power monitordoor lock monitorand some further spin-off devices.All builds are documented together with relevant background information for further study. For your convenience, there is a small PCB for most of the designs; you can also use a perf board. You don't need to be an expert but the minimum recommended essentials include basic experience with a PC, software, and hardware, including the ability to surf the Internet and assemble PCBs.And of course: A handle was kept on development costs. All custom software for the IoT devices and PCB layouts are available for free download from at Elektor.com.