Reviewing:
Fully Free Project Management Apps
Trello
MeisterTask
KanbanFlow
Freedcamp
Allthings
Bitrix24
Producteev
Avaza
Free Project Management Apps for Small Teams
Asana
Wrike
Podio
Redbooth
Free Project Management Apps for a Single Project
Teamwork Projects
Basecamp
Zoho Projects
Projectplace
Pivotal Tracker
Run a Project Management App on Your Own Servers
Taiga
Lavagna
Redmine
Odoo