You can use smart plugs like Sonoff S20[1] and flash your own firmware. They have the widely used ESP8266 inside. I use ESPurna[2] on them, which has many common integrations built-in (Alexa, MQTT, etc) and is very easy to extend further.

[1] https://www.itead.cc/smart-socket.html

[2] https://github.com/xoseperez/espurna