Multi-Provider Calendar Sync That Actually Works.

The problem every multi-calendar person has: Google Calendar shows one view, Outlook shows another, iCloud shows a third, and nobody can answer 'Am I free at 3pm?' without checking all of them. I built a Python/FastAPI backend that syncs from all three providers, deduplicates events by iCal UID (the same meeting across multiple accounts counts once), merges overlapping busy blocks, and computes unified availability.

OAuth tokens stored in macOS Keychain (never disk or database). Incremental sync via Google syncToken and Microsoft deltaLink for efficiency, with automatic full-sync fallback. React frontend with a custom CSS Grid calendar (not react-big-calendar) for responsive mobile views. APScheduler runs hourly auto-sync in the background.