keeper.shCalendar sync tool & universal calendar MCP server. Aggregate, sync and control calendars on Google, Outlook, Office 365, iCloud, CalDAV or ICS.

keeper.sh

Keeper is an open-source calendar synchronization tool that solves the problem of managing multiple calendars across different platforms. It aggregates events from Google Calendar, Outlook, Office 365, iCloud, CalDAV, and ICS sources, keeping them synchronized so you never miss scheduling conflicts across your calendars.

Key Features

• Multi-platform aggregation : Pull calendar events from Google, Outlook, Office 365, iCloud, CalDAV, and ICS sources simultaneously
• Intelligent sync engine : Automatically detect changes, push aggregated events to destinations, and remove stale entries
• MCP server support : Integrate calendar access into AI agents and automation workflows via Model Context Protocol
• Self-hosted option : Deploy on your own infrastructure with full data governance and all premium features included free

Use Cases

• Multi-calendar management : Keep business, work, and personal calendars in sync to prevent double-booking
• Event aggregation workflows : Consolidate events from multiple remote ICS/iCal sources into a single calendar
• AI agent integration : Enable intelligent scheduling assistants to read and manage your calendar via MCP protocol

Who Is It For

Keeper is designed for individuals and teams who juggle multiple calendars across different platforms and need reliable synchronization without sacrificing data privacy. It's ideal for self-hosted deployments where users want full control over their calendar data while avoiding the limitations of third-party sync services.