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 accessory refrigerator controller 230 V power monitor door lock monitor and 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.