work-cal-sync

Copies work Exchange/O365 calendar events from macOS Calendar.app to a self-hosted CalDAV server (Radicale, Nextcloud, Baikal, etc.).

If you use a self-hosted CalDAV server for your personal calendar and want your work appointments to show up there — without giving a third-party service access to your calendar data — this is for you.

How it works

• Reads your work Exchange/O365 calendar via EventKit — the same framework macOS Calendar.app uses. No Exchange credentials needed in the script; macOS manages authentication via your Internet Account.
• Writes to a dedicated calendar on your CalDAV server using the caldav Python library.
• Syncs with rsync --delete semantics: creates new events, updates changed ones, deletes cancelled ones.
• Runs every 15 minutes via launchd. No need to keep Calendar.app open.

Requirements

• macOS 13 (Ventura) or later, Apple Silicon or Intel
• Python 3.11+ (Homebrew recommended: brew install python)
• Your work Exchange/O365 account added to macOS via System Settings → Internet Accounts
• A CalDAV server with a dedicated calendar for work events

Install

git clone https://github.com/djdead/work-cal-sync.git
cd work-cal-sync
./setup.sh

setup.sh will:

1. Install Python dependencies (pyobjc-framework-EventKit, caldav, keyring)
2. Copy the script to ~/bin/
3. Run the interactive setup wizard
4. Install and load a launchd job to sync every 15 minutes

First-run setup wizard

On first run you will be prompted to:

1. Choose your work calendar — detected automatically from Exchange/O365 accounts in Calendar.app
2. Enter your CalDAV server URL — e.g. https://cal.example.com
3. Enter your CalDAV username and password — password is stored in macOS Keychain, never in the config file
4. Choose your target CalDAV calendar — fetched from your server so you can pick from a list
5. Set the sync window — defaults to 7 days back, 90 days forward

Configuration is saved to ~/.config/work-cal-sync/config.json. To reconfigure, delete that file and re-run the script.

Logs

~/Library/Logs/work-cal-sync.log

Reconfigure

rm ~/.config/work-cal-sync/config.json
python3 ~/bin/work-cal-sync.py

Uninstall

launchctl unload ~/Library/LaunchAgents/tel.dead.work-cal-sync.plist
rm ~/Library/LaunchAgents/tel.dead.work-cal-sync.plist
rm ~/bin/work-cal-sync.py
rm -rf ~/.config/work-cal-sync

To remove the saved password from Keychain, open Keychain Access, search for work-cal-sync, and delete the entry.

Tested with

• macOS 15 Sequoia, M4 Pro
• Exchange Online (O365)
• Radicale 3.x

Other CalDAV servers that follow RFC 4791 should work. Please open an issue if you test with another server.

Why not just use gSyncIt / CalDAVconnect / etc.?

• gSyncIt is Windows-only and syncs via Google Calendar as an intermediary.
• CalDAVconnect and similar cloud services route your calendar data through third-party servers — a non-starter if you self-host specifically to control your data.
• Outlook CalDAV Synchronizer is Windows-only and dead on new Outlook.
• macOS Calendar.app can display both your Exchange and CalDAV calendars simultaneously, but has no built-in way to copy events between accounts.

This script fills that gap: fully local, no cloud intermediary, no credentials stored in plaintext.

Limitations

• One-way only — work → personal CalDAV. Changes made on the CalDAV side are overwritten on the next sync.
• No attendee/RSVP data — EventKit exposes attendees but they are not currently written to CalDAV events.
• Exchange Online only — EWS/on-premises Exchange is not tested but may work since macOS abstracts the protocol.
• EWS deprecation — Microsoft is deprecating EWS for Exchange Online. This script uses EventKit (not EWS directly), so it should be unaffected as long as macOS continues to support Exchange accounts natively.

Contributing

PRs welcome. Known areas for improvement:

• Attendee/organizer fields
• Support for recurring event exceptions
• Configurable sync interval
• Tests