Kalender Sync

Kalender Sync automatically synchronizes calendars across multiple providers with customizable visibility levels.

Kalender Sync connects Outlook, iCloud, Google, GMX, WEB.DE, mailbox.org, Posteo, STRATO, and kSuite in real time with one- or two-way synchronization. Users can define visibility levels per sync, choosing between busy only, title and time, or full event details. The platform allows users to connect AI agents such as Claude and ChatGPT to manage schedules, plan days, and book events. Built in Munich by Paul Koch and Julius Hasenzahl, the tool is 100 percent GDPR-compliant and hosted on servers in Germany. It serves individuals, freelancers, and professionals juggling appointments across multiple calendars.

Kalender Sync at a glance

Best for: Software engineer, Founder
Runs on: Web, API
Pricing: Free plan; Basic plan available; Professional plan available; from 5 euros per month
Released: October 2026
Category: AI productivity tool
Website: kalender-sync.de

Key features

One-way or two-way calendar sync
Real-time schedule synchronization
Customizable visibility levels per sync
AI agent integration for Claude and ChatGPT
GDPR-compliant hosting in Germany
Multi-provider account management
Activity logging with timestamps

Use it for

Preventing double bookings across personal and work calendars
Sharing selective calendar availability with clients or colleagues
Allowing AI assistants to find free time and book appointments
Juggling appointments across multiple companies or freelance projects

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