DAViCal

DAViCal is an open-source calendar and contact server that synchronizes personal schedules using CalDAV and CardDAV standards. Its architecture stores appointments and address books in a private PostgreSQL database rather than commercial cloud infrastructure. This design ensures complete data ownership while maintaining compatibility with desktop and mobile calendar software.

Why DAViCal instead of Google Calendar

Google Calendar ties scheduling to a proprietary cloud where appointments, attendee lists, and event descriptions reside on remote servers. Daily organization requires navigating an ad-supported browser interface or mobile apps that report telemetry. DAViCal replaces that hosted model by acting as a private synchronization hub. Instead of managing days inside a vendor web portal, users interact with standard calendar clients already installed on their devices, such as Mozilla Thunderbird and mobile system calendars. Creating appointments, updating recurring events, and receiving notifications occur directly inside native desktop and phone apps without keeping a browser tab open.

For collaborative workflows, DAViCal handles calendar delegation and group coordination through server-side permissions. Users can publish shared project calendars, assign read or write rights, and check colleague availability using free-and-busy lookups. The primary workflow trade-off involves web access and administrative overhead. Google Calendar includes an integrated web interface accessible from any browser, whereas DAViCal functions strictly as a synchronization daemon and admin console. Users cannot view or edit their calendar grid in a web browser without installing a separate webmail client. Delivering meeting invitations to external attendees also requires configuring a mail server.

What it does well

• CalDAV and CardDAV synchronization: Keeps calendars, task lists, and address books aligned across computers and smartphones without commercial accounts.
• Granular calendar delegation: Allows users to grant colleagues or family members read-only or read-write access to specific calendars.
• Free and busy lookups: Enables meeting organizers to inspect participant availability and prevent scheduling conflicts across a group.
• Centralized address books: Stores shared contact details in standard vCard collections so households and teams maintain synchronized phone numbers.