An Alexa-compatible fake-Wemo switching socket for ESP8266
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WeMo (uPnP) compatible firmware for a Smart Switch

For the ESP8266 WiFi module.

Copyright (c)2018 Ross Bamford & Jake Randall.

Licensed under the MIT License - see LICENSE for details.

What is this?

This is a simple Arduino project that uses the ESP8266 WiFi module to support switching of relays, by emulating a WeMo device (using UDP multicast and HTTP). The aim of the project is to support switching of mains sockets using solid state relays, with control coming from the Amazon Echo.

It is currently tested with the Node MCU V2 development board, but should work with any ESP8266 module, although you may need to change some of the pin assignments in HardwareControl.h to suit your module and wiring.

This project now supports (and by default, expects) four sockets to be connected - these will appear in the Alexa app as four separate switches. The switches are controlled by relays connected to the appropriate digital outputs of the ESP8266. We use FOTEK SSR-40 DA relays, rated for 40A, but you should be able to use whatever you like.


  • Clone repo
  • Edit settings in WemoSockets.h to suit your WiFi environment.
  • Build with appropriate board settings (We use Sloeber which is awesome, but you can probably build with Arduino IDE.
  • Flash to device
  • Boot device. You should see the MCU LED light up, and the ESP LED flash while it searches for WiFi. Once it connects, both LEDs will be solid.
    • If it can't connect, it'll blink out SOS on the LEDs.
    • Connect a serial terminal to see what's happening.
  • Use the Alexa app to search for new smart home devices. She should detect it as a Belkin plug (that's what we emulate at the moment).


Huge props to this project, from which we learned a lot about getting stuff to work with Alexa!