European alternatives to TickTick

Todoist is a task management application and to-do list service.

MeisterTask is a web-based task management application that allows users to manage tasks in a customizable environment.

Zenkit To Do is a simple, collaborative task management tool to help you organize your tasks and be more productive.

Sorted³ is a task management app that helps you organize your day with a timeline view, combining tasks and appointments in one place.