Developer's Guide to Calendaring & Scheduling Standards

Practical guides, code examples, and best practices for building with iCalendar, CalDAV, CardDAV, vCard, and related protocols.

Data Formats

The core calendar data format — events, tasks, recurrences, and time zones (RFC 5545).

Contact data format — vCard 4.0 and the JSON-based vCard 5.0 / JSContact (RFC 6350, RFC 9553).

JSON-based calendar data model for web APIs and modern applications (RFC 8984).

Calendar access protocol — building clients and servers, libraries, and FAQs (RFC 4791).

Contact data access protocol — clients, servers, and libraries (RFC 6352).

Invitations, replies, and availability — iTIP, iMIP, Free/Busy, and CalDAV scheduling.

Time zone best practices, data sources, and TZDS.

VTODO component — task management in iCalendar.

Publishing calendar data — subscriptions, feeds, and sharing.

How spam exploits calendar invitations and how to prevent it.