It is estimated that trillions of devices will be interconnected over the next decade through the Internet of Things, demanding a huge effort from developers. The emergence of low-cost Espressif microcontrollers, with WiFi connectivity, allows independent developers to quickly become part of this process. This book is not intended to comprehensively teach you the theory, but to give you practical and fully functional solutions, in the form of complete programs. Much of the theory is already known by some of the readers, or may be found in many other textbooks. However, the programs presented here include great effort and have many original solutions following one of the basic paradigms of programming: "Keep i(o)t simple". In addition, the most important thing for such a book all the programs have already been verified by third parties, in this case students from Hyperion University, who have provided a very valuable feedback.