Dato - Better menu bar clock with calendar and time zones
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Clocker - Keep track of people in different time zones
BusyCal - powerful calendar app for macOS
Superpowered - Power through the day without your calendar
Google Calendar - Spend less time managing your day & more time enjoying it