Sync local calendars offline. Free, open source, no account needed.

CalSync is a free and open source alternative to OneCal, CalendarBridge, and Reclaim.ai. It syncs and merges events between local device calendars — no cloud servers, no accounts, no subscription.
When an event appears in one calendar, CalSync automatically copies it to another using a name you choose. All syncing happens directly on your device. Your calendar data never leaves your phone.
⭐ FREE & OPEN SOURCE — No subscription, no hidden costs, no ads
📱 WORKS OFFLINE — No internet connection required, ever
🔒 100% PRIVATE — Calendar data stays on your device, period
👤 NO ACCOUNT — No signups, no logins, no personal info collected
🔄 AUTOMATIC BACKGROUND SYNC — Detects calendar changes within seconds
📝 CUSTOM EVENT NAMES — Choose what synced events are called (e.g. "Busy")
📋 SYNC PREVIEW — See exactly what will change before it happens
🗑️ DELETION MIRRORING — Remove an event from source, removed from target
🔄 RECURRING EVENTS — Repeat events stay in sync automatically
🎨 MATERIAL YOU — Adapts to your device's dynamic color theme
Perfect if you need to:
• Sync work and personal calendars to share availability
• Prevent double-bookings across multiple calendars
• Manage client calendars as a freelancer or consultant
• Keep family calendars in sync without sharing login credentials
If you're looking for a OneCal alternative, CalendarBridge alternative, or Reclaim.ai alternative — CalSync is the offline, private, and completely free solution.
No ads. No tracking. No telemetry. Just calendar sync that works.