The NanoMCU is tiny, low-cost device featuring an ESP8266 SoC by Espressif Systems. At a price point of only 10 € (incl. shipping costs, price for 1 pc) this small all-in-one computer presents a strong offer.
The technical specifications of the ESP8266 have been released to the general public by the chip manufacturer along with an SDK, which led to many different firmwares being developed within an extremely short amount of time. Hardware manufacturers developed similar devices like the MOD-WIFI-ESP8266-DEV by Olimex or the ESP8266 add-on module for Arduino.
The key features of ESP8266 based devices like the NanoMCU are the ready to use integrated WiFi chip, direct IO, low power consumption, low price and open specifications.