Todoist
Freemium
Todoist: To-Do list and Task Manager.
Doit.im
Freemium
Doit.im is a Cross-platform Best Online GTD Service, which can sync with Phones.
Todo.txt
Open Source
todo.txt is software and operating system agnostic; it's searchable, portable, lightweight and easily Todo management software.
2Do
Commercial
2Do lets you take a completely different approach to managing your tasks. With its extremely simple-to-use interface.
Conqu
Freemium
Conqu is a simple yet powerful task management tool designed to help you conquer your inbox and get things done.
Things
Commercial
Things is a delightful and easy to use task manager.
TickTick
Freemium
TickTickis a cross-platform to-do list app & task manager helps you to get all things done and make life well organized.
Bitrix24
Freemium
Bitrix24 is a free (for small businesses) social enterprise platform.
Tasque
Open Source
Tasque is an open source task management application.
ActiveInbox for Gmail
Commercial
ActiveInbox for Gmail is an email management software for Gmail.
Compare Nozbe with alternatives
Compare ActiveInbox for Gmail and Nozbe and decide which is most suitable for you.