Every now and again we setup and Minecraft Server and play through a mod pack for a few months. I wanted to make a way to check if someone was connected to server and notify me. Minecraft has a built in “query” API to help facilitate this, however there is little documentation on how it works apart from some PHP code from Dinnerbone. I wanted to make a Arduino implementation which could run independently without a computer connected, using the Ethernet shield to handle all of the communication to the Arduino server. After a lot of time with Wireshark and this wiki I was able to create my own Arduino Library to query a Minecraft Server. You can download the code for this library using the button above.