There are many alternatives to Todoist for Linux if you are looking for a replacement. The best Linux alternative is Org mode, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Todoist and loads of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Todoist are Remember The Milk (Freemium), Super Productivity (Free, Open Source), Zoho Notebook (Free Personal) and Taskwarrior (Free, Open Source).
A self-hosted open source system for the long-term management of personal information. It is a combination of a web-based application intended for desktop use, and an Android mobile reader application.
DayTasks lets you easily manage adding new tasks, removing tasks, marking tasks complete, archiving completed tasks to your done.txt file, and even filtering and searching through tasks in a simple way that lets you find certain projects or contexts easily.