Redmine

Open Source

Redmine is a flexible project management web application.

Trac

Open Source

Trac is an open source, Web-based project management and bug tracking system.

Mantis Bug Tracker

Open Source

Mantis Bug Tracker is a free and open source, web-based bug tracking system. The most common use of MantisBT is to track software defects.

Geary

Open Source

Geary is an email application built around conversations, for the GNOME 3 desktop. It allows you to read, find and send email.

Mutt

Open Source

Mutt is a text-based email client for Unix-like systems.

Bitrix24

Freemium

Bitrix24 is a free (for small businesses) social enterprise platform.

Zimbra Desktop

Free Personal

Zimbra Desktop is an offline client that lets you manage various email accounts in one desktop tool.

Open365

Open Source

Open365 is an all-in-one productivity suite, based on KDE, Seafile, LibreOffice, Docker, and Jitsi.

Kontact

Open Source

Kontact is a personal information manager and groupware software suite developed by KDE. It supports calendars, contacts, notes, to-do lists, news, and email.

Evolution

Open Source

Evolution is the official personal information manager for GNOME.

Mailspring

Freemium

Mailspring is a multi-platform email client.

Claws Mail

Open Source

Claws Mail is a free and open-source, GTK+-based email and news client. It offers easy configuration and an abundance of features.

Ora

Commercial

Ora is a real-time all-in-one workspace for teams.

Phabricator

Open Source

Phabricator is a suite of web-based software development collaboration tools.

ProjectLibre

Open Source

ProjectLibre is an open source, freely available project management software system intended ultimately as a standalone replacement for Microsoft Project.

Kontact - KMail

Open Source

KMail is the email component of Kontact, the integrated personal information manager from KDE.

FogBugz

Commercial

FogBugz is an integrated web-based project management system featuring bug/issue tracking, discussion forums, wikis, customer relationship management, and evi…