DropTask
Task Coach
EssentialPIM
Todo.txt
GTDNext
Todoist
Meistertask
CherryTree
Elementool
Jira
DropTask
ElementoolTask Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
GTDNext - About Us.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.