Microsoft SharePoint!

Basecamp is a web-based project collaboration tool that allows groups of people to share files, meet deadlines, assign tasks, and centralize feedback.

HumHub is a free social network software and framework built to give you the tools to make teamwork easy and successful.

Tiki Wiki CMS Groupware is a full-featured, web-based, multilingual (40+ languages), tightly integrated, all-in-one Wiki+CMS+Groupware, Free Source Software (GNU/LGPL), using PHP + Smarty, MySQL, Zend Framework, jQuery and Bootstrap. Tiki can be used to create all kinds of Web applications, sites, portals, knowledge base, intranets, and extranets. It is actively developed by a very large international community.

XWiki is a powerful Open Source collaborative platform allowing companies of all sizes to save time and money while enhancing collaboration on both team and organizational level. Being focused on efficient communication and collaboration, XWiki redefines the value of business knowledge by allowing any user to access critical information in a fast and efficient way while reducing the organizational silos.

eXo Platform is a cloud-ready enterprise portal and user experience platform-as-a-service (UXPaaS) for building and deploying transactional websites, managing web and social content and creating gadgets and dashboards. Built on open standards and open source technologies, eXo Platform has the features and extensibility of a UXP and the cloud architecture to build public and private clouds.

Alfresco is the leading open source enterprise content management system built by the most experienced team in the industry drawn from Documentum®, Vignette® and Interwoven®. Twenty years of experience drove us to believe that the Enterprise Content Management industry was driven by:

Nuclino is the easiest way to organize and share knowledge in teams. Create real-time collaborative documents and connect them instantly like a wiki. Use the tree, board, and graph view to explore and organize your knowledge visually. It's great for meeting notes, product requirements, docs, decisions, and more.

With Samepage, you can put all your project information on one page and collaborate with your team in real time. Samepage brings together an entire suite of project management tools, awesome communication features, and built-in integration with the apps you use. Everything you need to move projects forward, without leaving Samepage.

Kolab Now, formerly MyKolab, is a fully featured secure collaboration and communication service that is easy to use on any device.

ClockingIT is a free hosted application,keeping track of all yourtasks and the time youspend on them.Extensive featuresProject Management,Collaboration and Time Tracking

5pm is a web based project management application with a smart customizable interface. Email integration, iCalendar and RSS feeds, Timeline view and Reports are just a few features to mention. Free trial (no credit card required) is available.

Open Atrium is an installation profile for Drupal.

The easiest way to collaborate on projects and ideas. MOOVIA is an enjoyable and secure social environment to host your team`s projects, tasks, meetings, ideas, messages and documents. It's a social collaboration platform designed for teamwork that improves communication, productivity and engagement.