ESP8266 has made it possible for hobbyists and makers to develop IoT applications in simple and inexpensive ways. This article shows an example of making a very simple temperature and humidity logger using ESP8266 that uploads the data directly to a cloud service, such as ThingSpeak, and allows to visualize the data in real time. The ESP8266 module used in this project is WeMOS’ D1 Mini board. Because the D1 board comes with the CH340G USB to UART converter module and a micro USB connector preinstalled on board, all you need is an USB cable to upload your program to the ESP8266. For temperature and