On-Call Schedule - Quickly update your on-call schedule on Google Calendar
Google Calendar - Spend less time managing your day & more time enjoying it
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Mixmax Calendar - The fastest way to schedule meetings with anyone, anywhere
Cron - Cron Calendar.
Sunsama - Calendar and scheduling for teams