Sonoff Basic WiFi Smart Switch Teardown
The Sonoff Basic is a low cost IoT WiFi connected relay which you can use to switch things like lights or small fans. The Sonoff is particularly hackable, since it brings out all the pins needed to reflash the firmware and add remote buttons/indicators. Third party firmware images like Tasmota (https://tasmota.github.io/docs/) allow you to directly control these using MQTT or as a Hue device.
Sonoff Basics are available on Amazon (https://amzn.to/2uwKYea) as well as many other online retailers. Sonoff (https://sonoff.tech/) also has many other form factors of relays other than the Basic supported by Tasmota.