Foam
Foam is a personal knowledge management and sharing system inspired by Roam Research, built on Visual Studio Code and GitHub.
Group-Office is an enterprise CRM and groupware tool. Share projects, calendars, files and e-mail online with co-workers and clients. Easy to use and fully customizable.
Open source free community version features : E-mail, Calendar, File sharing, Address book, Tasks, Notes, Newsletters.PHP based.Very simple to install and update in Debian 8.x