Hysen Labskeeper.sh
Calendar sync tool & universal calendar MCP server. Aggregate, sync and control calendars on Google, Outlook, Office 365, iCloud, CalDAV or ICS.
Keeper.sh syncs calendars and exposes them through an MCP server
An open source calendar aggregation tool that pulls events from Google, Outlook, iCloud, CalDAV, and ICS sources and pushes them to one or many calendars.
What it does
Keeper.sh is a calendar syncing tool. It pulls events from Google Calendar, Outlook, iCloud, Fastmail, a CalDAV server, or remotely hosted iCal and ICS links, and pushes them to one or many destination calendars so time slots align across accounts. Google, Outlook, iCloud, Fastmail, and CalDAV are first class integrations usable as source or destination, while iCal and ICS links are pull only.
Features and interface
The tool supports incremental syncing on Google and Outlook using provider sync tokens, per source privacy controls that can strip event names and details, a REST API under /api/v1 authenticated with tokens, and a combined iCal feed. It also runs as an MCP server so AI agents can manage calendars through one interface. The project is AGPL-3.0 licensed and every Pro feature is included when self hosted.
Running and scale
The recommended path is a hosted version, while self hosting runs behind a Caddy reverse proxy with automatic TLS on keeper.localhost, using Docker Compose for PostgreSQL, Redis, and the API, web, MCP, cron, and worker services. The August 2026 snapshot shows 1,253 stars, 46 forks, and 140 open issues, reflecting a widely used open source calendar tool.
Editorial conclusion
Keeper.sh is AGPL-3.0 licensed and records 1,253 stars with 46 forks as of August 2026. It aggregates calendars from major providers and exposes them through both a REST API and an MCP server for agent access.
Community notes