Top Alternatives to Apple Calendar

Microsoft Outlook is a comprehensive personal information manager designed for managing email, contacts, calendars, and tasks.

Lightning is a comprehensive calendar and task management add-on for Mozilla Thunderbird and Seamonkey, designed to integrate seamlessly with email. It offers robust features for scheduling, task tracking, and synchronization with various online calendar services, enhancing productivity directly within your email client.

Fantastical is a powerful and intuitive calendar and task management application designed for macOS, iOS, and watchOS. Known for its natural language processing engine and elegant interface, it simplifies scheduling and staying organized across all your Apple devices.

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.

Calvetica is a highly-regarded calendar and time management application designed specifically for iPhone and iPad, praised for its speed and intuitive user interface to quickly create, view, and manage events.

Etar is a free and open-source material design calendar application for Android, prioritizing privacy and a clean user experience. It focuses on core calendar functionalities like event management and reminders, offering data export/import and syncing capabilities without ads or excessive features.

VueMinder Calendar is a comprehensive calendar and task management application for Windows, designed to help users organize their schedules and boost productivity. It offers a wide range of features including robust synchronization options, customizable views, and advanced reminder capabilities, making it suitable for both personal and professional use.

Microsoft Calendar, part of the Outlook suite, is a robust online calendaring platform designed for scheduling, organization, and collaboration. It allows users to manage appointments, events, and tasks effectively, integrate with other services, and share schedules with others.

Microsoft Mail and Calendar is the default email and calendar client included with Windows, providing integrated tools to manage your communications and schedule.

BusyCal is a powerful desktop calendar application for Mac, designed to enhance productivity and organization. It offers a robust set of features for managing events, tasks, and reminders, with seamless integration across various calendar services like iCloud, Google Calendar, and Exchange.

KOrganizer is a comprehensive calendar and scheduling application, part of the integrated KDE Kontact suite. It provides robust tools for managing events, tasks, and deadlines, with extensive connectivity options and customization.

aCalendar is a feature-rich calendar and task management application designed for users who need robust synchronization, detailed event management, and a user-friendly interface.