Blog
Finding a free slot across Google, Outlook and iCloud
Each calendar API answers "when is this person busy?" differently. Here's what each one gives you, and how to merge them without double booking.
Three ways a calendar tells you what changed
Google sync tokens, Microsoft Graph delta links and CalDAV sync-collection all answer "what changed?", and each one fails in its own way.
One standup, three calendar APIs
How Google Calendar, Outlook and CalDAV store the same recurring meeting and its exceptions, and what it takes to put one API over all three.