OctoPrint provides a snappy web interface for controlling consumer 3D printers. It is Free Software and released under the GNU Affero General Public License V3 by Gina Häußge.
Its website can be found at http://www.octoprint.org.
Jneilliii wrote a plugin to control your Sonoff device with tasmota firmware via OctoPrint, for example shutdown the printer after a print has finished.
Repository: https://github.com/jneilliii/OctoPrint-Tasmota