About

Keeper.sh is a simple & open-source calendar syncing tool. It allows you to pull events from your Google Calendar, Outlook, iCloud, Fastmail, CalDAV server, or remotely hosted iCal and ICS links, and push them to one or many calendars so the time slots can align across them all. Google, Outlook, iCloud, Fastmail, and CalDAV are first-class integrations that can each be used as a source or as a destination, while iCal and ICS links are pull-only. It also serves as a global MCP server and API for you or your agents to manage all your calendars from one convenient interface.

The recommended way to run it is the hosted version at keeper.sh: the same code, minus the server, the domain, the upgrades, the backups and the Google and Microsoft sign-in apps you would otherwise register yourself. Self-hosting is a first-class path and every Pro feature is included when you self-host — that is not a trial, and it is not going away. It costs you the upkeep instead of the $5.

Features

• First-class Google Calendar, Outlook, iCloud, Fastmail, and CalDAV integrations, each usable as a source or a destination
• Pull-only ingestion of remotely hosted iCal and ICS links
• Incremental syncing on Google and Outlook using provider sync tokens rather than refetching everything
• Event content agnostic syncing engine
• Push aggregate events to one or more calendars
• Per-source privacy controls to strip event names, descriptions, and locations, replacing the title with a {{calendar_name}} or {{event_name}} template
• REST API under /api/v1 authenticated with API tokens
• MCP (Model Context Protocol) server for AI agent calendar access
• Combined iCal feed you can subscribe to from any calendar app
• Open source under AGPL-3.0
• Easy to self-host
• Easy-to-purge remote events

Bug Reports & Feature Requests

If you encounter a bug or have an idea for a feature, you may open an issue on GitHub and it will be triaged and addressed as soon as possible.

Contributing

High-value and high-quality contributions are appreciated. Before working on large features you intend to see merged, please open an issue first to discuss beforehand.

Local Development

The dev environment runs behind HTTPS at https://keeper.localhost using a Caddy reverse proxy with automatic TLS. The .localhost TLD resolves to 127.0.0.1 automatically per RFC 6761 — no /etc/hosts entry is needed.

Prerequisites

• Bun (v1.3.11+)
• Docker & Docker Compose

Getting Started

bun install

Generate and Trust a Root CA

The dev environment runs behind HTTPS via Caddy. You need to generate a local root certificate authority and trust it so your browser accepts the certificate.

mkdir -p .pki
openssl req -x509 -new -nodes \
  -newkey ec -pkeyopt ec_paramgen_curve:prime256v1 \
  -keyout .pki/root.key -out .pki/root.crt \
  -days 3650 -subj "/CN=Keeper.sh CA"

Then trust it on your platform:

macOS

sudo security add-trusted-cert -d -r trustRoot \
  -k /Library/Keychains/System.keychain .pki/root.crt

Linux

sudo cp .pki/root.crt /usr/local/share/ca-certificates/keeper-dev-root.crt
sudo update-ca-certificates

Start the Dev Environment

bun dev