open source collaboration platforms

See the following -

Getting Started With Carbonio, An Open Source Collaboration Platform

In recent years, interest in using open source collaboration platforms to enhance business productivity increased. Proprietary software has managed to overwhelm customers with a maze of licensing requirements and pay-to-play features that many companies don't want to manage. On the other hand, open source offers alternatives that give companies the liberty of choice and allow new businesses to enter existing markets easier with more control over upfront costs.