Readdle's Calendars app, which combines tasks, to-dos, and reminders, is now available for Macintosh. Calendars by Readdle is part of the company's collection of Mac applications.
Fans of the Calendars by Readdle app will be happy to know that they don't have to pay extra for cross-device use because the Mac app syncs up with the iPad version. You can use the main calendar part of the app for free, but you won't get the integration features with apps like Apple's Reminders as well as the weeklyplanner feature. It can be used to create and launch video meetings.
Fantastical, which has Mac, iPad, and iPhone apps but costs twice as much as Readdle, is a comparable app. You can type things like "breakfast with Pavan at noon tomorrow at Hidden Grounds" into the app and it will convert to a calendar item. Fantastical doesn't work on older Macs, but Calendars by Readdle does. The scheduling feature from Fantastical can help you get an opening even if you don't use the app.
On the Mac App Store, you can find Calendars for free. You can get a seven-day free trial of the Pro version if you want to see how the app works.