Todoist is a project management application for personal and professional productivity. It allows users to manage their tasks from a smartphone, tablet or computer. The app is free, though additional features to enable collaboration are available in a paid version. Todoist was created in 2007 by startup Doist. As of June 2014, it has 2 million users. 
In Todoist, tasks are either aligned to projects or sit loosely in an inbox. Projects may contain other sub-projects, and tasks may contain sub-tasks. Tasks can be filtered by label, date or priority. Completion of tasks results in "karma" points being awarded to the user, introducing an element of gamification.
Launched in January, 2007 by Amir Salihefendic, Todoist was soon thereafter named the "startup of the week" by ReadWriteWeb, having called it "astonishing".
In January, 2011, Todoist received USD $40,000 of equity-free funding from Start-Up Chile. As of then, Todoist maintained an office in Santiago, Chile until 2013 when the headquarters has moved to Porto, Portugal.
On June 27, 2012, Todoist became the first fully HTML5-based task manager web application, enabling offline storage and access to tasks.  < The HTML5 overhaul resulted in exceptional speed, allowing the application to load in under 100 milliseconds and marked the software’s first 350,000 user milestone.
Todoist Premium Accounts
The premium version of Todoist costs USD $29 per year. Todoist Premium features include unlimited automatic synchronization across devices, platforms and computers; mobile and email reminders; unlimited note and file attachments; SSL encryption; task search; iCalendar task access; the ability to add emails as tasks; project templates; and automatic backups.
Todoist is available on Windows, iOS and Android platforms. Launched in November 2012, the native application is free with an option to upgrade. In October 2013, Todoist was upgraded for iOS 7.
In March 2015, Todoist version 10 was released for iOS.
This version included interface design changes to improve consistency with other platform versions as well as Gesture-based actions, a "Quick Add" feature, The ability to edit multiple tasks at once and options to use color themes in the interface.
In March 2016 version 11 was released for iOS, this was the first version to have native support for Watch OS, however there were reports of crashes and bugs, despite issuing a bug fix release a few days later the overall rating for the software was reduced from an average of 4.5 to 2.5 stars on the Apple App Store, with a significant number of 1 star reviews.
In addition, several reviewers commented that they believed their concerns were not being addressed by the company.