Todoist, Microsoft To Do, Things, ToDoList, Workflowy, Focalboard, Taskade, Org mode, Tasks.org, Task Coach, Remember The Milk, sleek, Zanshin, GoTasks, Calcurse, The Big Picture, QTodoTxt 2, Reddynote, Hiveminder, Thymer, TaskOnBot, MyAsana are some alternatives to GTasksTo-Do List.