Cron - Cron Calendar.
ScreenTime - Show your macOS desktop on FaceTime
Vimcal - Vimcal is the world’s fastest calendar, beautifully designed for people who work remotely and live in their calendars.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
KosmoTime - The to do list with super powers
zcal - zcal is the fastest way to schedule every meeting for Free and make it personal.