The ESP8266 is an ingenious little chip. It's fully integrated - no external balun required unlike many of its competitors, no calibration by board manufacturer

The ESP8266 is an ingenious little chip. It's fully integrated - no external balun required unlike many of its competitors, no calibration by board manufacturers, just drop in and use. They reached the scales required to justify their NRE costs by making it a dual-use chip that could serve both as a a WiFi interface for cheap Android tablets and a standalone IoT design.