GroupSquares is a project created by Vladimir Sinitsyn, a programmer and entrepreneur. This place includes collection of effective, lightweight and flexible tools for groups/teams. GroupSquares tools support all popular platforms (Windows, Mac, Linux, IOS, Android etc.).
Your group/team should have/manage your own server to use some GroupSquares tools. You can use VPS/VDS hosting or physical server. It is not easy like Facebook/Twitter usage (common database for all users worldwide), but it is secure and you have full control.