GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.
Confluence - Confluence is content collaboration software that changes how modern teams work
GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab
Slack - A messaging app for teams who see through the Earth!
BitBucket - Bitbucket is a free code hosting site for Mercurial and Git. Manage your development with a hosted wiki, issue tracker and source code.
Yammer - Yammer is a leading enterprise social network used by more than 200,000 companies worldwide, including 85% of the Fortune 500, to get work done smarter and faster. Sign Up Today.