Pusher Beams - Send push notifications programmatically at scale

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.

Notisave - Notisave – Status and Notifications Saver is an exceptional tool created and published by Tenqube Inc.

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

Notifiee - Send cross-channel team notifications from your app ⚡️

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