Google Tasks - to-do list app that integrates with Gmail and Google Calendar
CiraSync - CiraSync is a program that syncs and shares office 365 GAL contacts and calendars to smartphones.
Things - Things is an easy to use task manager.
Simplish - Simplish is a day planner software that is used for time management.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Clariti.app - Clariti is a team communication app that uses Artificial Intelligence to combine emails, chats, documents, calendar events and feeds on the same topic, in rich context-based Conversations to ensure your communication stays focused & organized.