eXo Platform - Digital workplace solution

EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.

ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.

Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

Apache Airflow - Airflow is a platform to programmaticaly author, schedule and monitor data pipelines.

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.