Persian Calendar - Free and open-source Persian Calendar
Lightning Calendar - Organize your life — it’s about time!
SSuite My Calendar Diary - A portable calendar and diary for people on the move...
Google Calendar - Spend less time managing your day & more time enjoying it
Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
Morgen.so - All-in-one Calendar, Tasks & Scheduler. Morgen is the single hub for everything that revolves around time management.