Wekan!

Taiga is a full featured project management platform for startups and agile developers & designers who want a simple, beautiful tool that makes work truly enjoyable.

Trusted by 11,000+ businesses, JIRA is the leading bug tracking, issue tracking and project management tool. JIRA combines issue tracking, agile project management, customisable workflow, and a pluggable integration framework to increase the velocity of your software development team.

Kanboard is a simple visual task board software.

Take your tasks anywhere with this feature-packed application.

Task Coach is a well-structured, portable, open source todo / task manager (supporting 50 languages). It grew out of frustration that well-known task managers, such as those provided with Outlook or Lotus Notes, do not provide facilities for composite tasks. Over time, Task Coach has added effort tracking, budgeting, notes, priority adjusting, reminders, and many other features.

An easy to use, web-based to-do list. Get organized, stay motivated, and be more productive.

Any.DO helps you get things done with your friends in a simple & elegant way. It's free, simple & fun.

TickTick is your daily must-have to-do & task list to make all things done and get life well organized.

Producteev is an online task management tool that serves as your full Productivity platform (Task and Project Management, Files Sharing, Internal Communication and Productivity Apps Aggregation).

A Kanban-inspired app for keeping track of things that need to get done.

Track your tasks and projects in a plain text file, todo.txt. A todo.txt is software and operating system agnostic; it's searchable, portable, lightweight and easily manipulated.

Open source Trello-like kanban board. Based on Restya platform.

Quire is a new-generation collaborative task management tool for organizing tasks in a tree-like structure wrapped in simple and user-friendly UI.