Apps to Built-in Calendar

Buffer is a comprehensive social media management platform designed to help individuals and businesses schedule posts, analyze performance, and engage with their audience across various social networks.

Apple Calendar is a personal calendar application developed by Apple Inc., designed to seamlessly integrate with your Apple ecosystem whether you are on macOS or iOS. It allows you to manage your schedule, appointments, and events efficiently, synchronizing across all your devices.

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.

ProtonMail is a leading secure email service utilizing end-to-end encryption and zero-access architecture to protect user privacy. Developed by scientists at CERN, it offers a robust and user-friendly platform for sending and receiving confidential communications.

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

Kolab Community is a comprehensive, free, and open-source groupware suite designed for collaborative work. It provides integrated email, calendar, contacts, and tasks functionalities, empowering individuals and teams to communicate and manage their data efficiently and with a strong focus on data privacy.