ESP8266 – The Little Beast!
The esp8266 chip is made by Espressif Systems.
ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi networking functions from another application processor.
The chip have both certifications FCC and CE. You can sell your products to the mass market.