Cron - Cron Calendar.
Tactical Time Blocker - Daily highlights & adaptive time blocking template
KosmoTime - The to do list with super powers
Taskful - Deadlines, meet your match.
Vimcal - Vimcal is the world’s fastest calendar, beautifully designed for people who work remotely and live in their calendars.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.