There are 1 repository under matchmaking-server topic.
A Multiplayer lobby example project in Unity using the SocketWeaver SDK
A MatchMaker Exchange server
Anet (aka Activenet, Activlink) was created at Activision in 1995, and was used by various companies to create twenty-odd multiplayer games for MS-DOS, Macintosh, Windows 95, and Linux between 1995 and 2001. Activision has graciously agreed to release the source code for Anet under the GNU Lesser Public License. http://kegel.com/anet/
Simple matchmaking system
C# Server for a Matchmaking API
Simple match making server for online games
Tic Tac Toe - Matchmaking Server