GeneXus Server is a product designed to facilitate the teamwork of developers. It offers simple, powerful and efficient solutions to the problems faced daily by teams of developers.
GeneXus Server automates knowledge integration while strongly improving the capacity of teamwork with GeneXus.
A Knowledge Base administered by GeneXus Server enables authorized developers to send and receive modifications from the Server Knowledge Base, while centralizing business knowledge and integrating the development team.
This is possible regardless of whether team members are scattered around the world or all together at one location.

Take a look at Team Development with GeneXus Server to get an overview of how Team Development with GeneXus Server works.
Public GeneXus Servers, called Sandbox, are a set of free services provided by GeneXus for all the GeneXus Community.
Also, you can learn GeneXus by samples, share & build together making your Knowledge bases open source in the Open GeneXus Servers.
Learn more here.