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Kalender-Sync

Kalender-Sync

SaaS tool for synchronizing calendars across platforms — Google, Microsoft, Apple (CalDAV), and iCal feeds.

TypeScriptNode.jsPostgreSQLCalDAVOAuthSaaS
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The Problem

Anyone using multiple calendars for work and personal life — Google, Outlook, Apple — knows the struggle: events are scattered, scheduling conflicts go unnoticed, and manual sync is error-prone.

The Solution

Kalender-Sync is a SaaS tool that automatically synchronizes calendars from different providers. Users connect their accounts via OAuth or CalDAV and choose which calendars to mirror where.

Technical Highlights

  • Multi-Provider Architecture: Abstracted provider interface for Google Calendar, Microsoft Graph, Apple CalDAV, and iCal feeds
  • Delta-Sync: Efficient incremental synchronization via change tokens instead of full sync
  • Encryption: ChaCha20-Poly1305 for all stored OAuth tokens and CalDAV credentials
  • Job Queue: pg-boss v10 for reliable background sync with retry logic
  • Stack: TypeScript, Node.js, PostgreSQL, Drizzle ORM, Astro (Landing Page)

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