Motion App, Google Calendar, Calendly, Fantastical, BusyCal, Rainlendar, Cron Calendar, Morgen, Reclaim, Lightning Calendar, Calendar Buddy, Proton Calendar, Amie, HEY Calendar, Sunsama, Calendar 366, Timepage, Mayday, MeetingBar, Itsycal, zcal, Nextcloud Calendar, Zoho Calendar, Easy!Appointments, Kalendar, Calendarscope are some alternatives to Notion Calendar.