Calendarserve

Calendarserver is a free and open-source server software that implements the CalDAV protocol, allowing users to share and synchronize calendars. Developed by the same team that created Mailman and known for their contributions to GNUstep, Calendarserver is designed to be a robust and scalable solution for calendaring needs. It provides functionality for managing events, to-do lists, and other calendar-related data across multiple devices and users.

The core of Calendarserver's offering lies in its adherence to open standards, primarily CalDAV. This ensures interoperability with a wide range of client applications, including popular email and calendar clients found on desktop operating systems and mobile devices. Users can connect their preferred clients to Calendarserver and sync their calendars seamlessly.

Calendarserver is typically deployed on a server and can be integrated with other services. It supports features such as calendar sharing among users, invitation management, and recurring events. Its open-source nature means it can be freely used, modified, and distributed, making it an attractive option for individuals and organizations seeking self-hosted or customizable calendaring solutions. Installation and configuration can vary depending on the operating system and deployment environment.