Open source Collaborative software

Kolab

The Kolab.org Community is a Free Software initiative building a unified communication and collaboration system that you can install on your own server. (GPL)

Cross-platform

Loomio

Loomio is an open-source web application that helps groups make better decisions together. Bring together the right people and the right information. Accessible, easy to use, customisable, with fine-grained options for privacy and security. (AGPL)

Cross-platform

Mattermost

Mattermost is an open source, self-hosted Slack-alternative. As an alternative to proprietary SaaS messaging, Mattermost brings all your team communication into one place, making it searchable and accessible anywhere. (MIT)

Cross-platform

OnlyOffice

OnlyOffice is a multifunctional office suite that enables you to store and co-edit documents, manage projects, email correspondence and customer relations in one place. (AGPL)

Cross-platform

Open-Xchange

Open-Xchange is the information and knowledge headquarters of a company. Open-Xchange combines e-mail, appointment, contact and task management with intelligent document management. (GPL)

Cross-platform

Zarafa

Zarafa open source offering consist of the Zarafa server, Z-Merge, the Zarafa IMAP/POP3/iCal gateway, the Zarafa Administration Console, the Zarafa WebAccess and many other tools and services. (AGPL)

Cross-platform

Zimbra

Zimbra is a client and server platform for next-generation messaging and collaboration. (MPL)

Cross-platform

Zulip

Zulip is a powerful, open source group chat application that combines the immediacy of real-time chat with the productivity benefits of threaded conversations. Zulip is 100% open source software, built by a vibrant community of hundreds of developers from all around the world. (Apache)

Linux

8 applications