Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Google Calendar - Spend less time managing your day & more time enjoying it
BusyCal - powerful calendar app for macOS
Lightning Calendar - Organize your life — it’s about time!
Superpowered - Power through the day without your calendar
HEY - Email at its best, new from Basecamp.