Todoist, Microsoft To Do, ToDoList, TickTick, Habitica, Wekan, Google Tasks, Org mode, Tasks.org, Remember The Milk, sleek, SkedPal, Flow Task Manager, TodoListMe, d:DONE, Focuster, PopDo, Evidme, jiPANEL, Do Now, TaskOnBot, Sendtask, Arktik, Efeqti are some alternatives to Vikunja.