In the old days, spies eavesdropped on each other using analog radio bugs ... Enter the ESP8266 and some programming wizardry. [Sebastian] is using a NodeMCU but suggests that it could be pared ...

The various development boards such as the NodeMCU or Wemos D1 make working with the ESP8266 an absolute breeze ... programming jig that uses pogo pins. If you have to program these boards ...