Need free collaboration software? Bitrix24 is it. Available in cloud or on premise with 35+ free collaboration tools, Bitrix24 lets you discuss ideas, share files, create workgroups, set team tasks, chat individually or in groups, hold videoconferences and do much more.
Please read Bitrix24 manual, if you'd like to know
how different collaboration work. And if you want to buy on premise editions of Bitrix24 that come with API, CMS and source code, please
download trial version here.