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Connect CalDAV Calendar

For Fastmail, Nextcloud, SOGo, and other CalDAV providers

What is CalDAV?

CalDAV is an open standard protocol for accessing calendar data over the internet. Many calendar services support CalDAV, making it a flexible option for connecting calendars.

Popular CalDAV providers include: Fastmail, Nextcloud, SOGo, Radicale, Baikal, Synology Calendar, and many others.

What You'll Need

1. Server URL

The CalDAV server address from your provider (e.g., caldav.fastmail.com)

2. Username

Usually your email address or account username

3. Password

Your account password or app-specific password

Popular CalDAV Providers

Server URL: https://caldav.fastmail.com
Username: Your Fastmail email address
Password: Your Fastmail password (or app password if 2FA enabled)

📚 Fastmail CalDAV documentation

Server URL: https://your-nextcloud.com/remote.php/dav
Username: Your Nextcloud username
Password: Your Nextcloud password or app password

Tip: For better security, generate an app-specific password in Nextcloud: Settings → Security → Devices & sessions → Create new app password

Server URL: https://your-sogo-server.com/SOGo/dav
Username: Your SOGo username (often email@domain.com)
Password: Your SOGo password

Server URL: https://your-nas-address.com:5001/calendar
Username: Your Synology DSM username
Password: Your Synology DSM password

Make sure Calendar package is installed and CalDAV is enabled in Calendar settings.

Step-by-Step Guide

Gather Your CalDAV Details

Before connecting, you need to find your CalDAV server information. This is typically found in:

Your provider's help documentation
Account settings page
Email from your provider when you signed up

You'll need:

CalDAV Server URL - e.g., caldav.example.com or https://example.com/dav
Username - Usually your email address
Password - Your account password or app-specific password

Can't find your CalDAV details? Contact your calendar provider's support or check their documentation for "CalDAV" or "third-party calendar access".

Go to Calendar Connections

In SyncMyDay, navigate to Calendars in the menu, or go to the Calendar Connections page.

Go to the Calendar Connections page

Click "Connect CalDAV"

Find and click the CalDAV (Generic) button.

Calendar provider options with CalDAV button

Click the "Apple / CalDAV" button

Enter Your CalDAV Credentials

Fill in the connection form with the details you gathered:

CalDAV Server URL

Enter the full CalDAV server address. Examples:

https://caldav.fastmail.com
https://nextcloud.example.com/remote.php/dav
caldav.example.com (we'll add https:// automatically)

Username

Usually your email address (e.g., you@example.com) or username

Password

Your account password or app-specific password (if your provider requires it)

App-Specific Passwords

Some providers (like Fastmail with 2FA) require app-specific passwords instead of your regular password. Check your provider's documentation.

Enter your CalDAV server details

Test Connection

Click "Connect" or "Test Connection". SyncMyDay will:

Verify the server URL is reachable
Authenticate with your credentials
Discover available calendars

This usually takes 5-10 seconds.

Select Calendars

Once connected, you'll see a list of all calendars available on your CalDAV server. Select which ones you want to sync.

Typical calendars you might see:

Personal - Your main calendar
Work - Work-related events
Family - Shared family calendar
Any custom calendars you've created

Calendar selection with CalDAV calendars

Select which calendars you want to synchronize

Connection Complete!

Your CalDAV calendar is now connected and ready to use!

✅ What's Next?

Your CalDAV calendar is ready for sync rules
Events will sync every 15 minutes
You can now create sync rules!

Note: CalDAV doesn't support real-time webhooks, so we poll for changes every 15 minutes.

Your CalDAV calendar is successfully connected and active

Troubleshooting

"Connection failed" or "Unable to connect"

Check these common issues:

Server URL format: Make sure it includes https:// or let us add it automatically
Trailing slashes: Try with and without trailing slash (/) at the end
Port number: Some servers need explicit port (e.g., :8443)
Self-signed certificates: If using self-hosted, ensure your SSL certificate is valid
Firewall: Make sure your CalDAV server is accessible from the internet

"Authentication failed" or "Invalid credentials"

Common causes:

Incorrect username or password
Need to use app-specific password (if 2FA is enabled)
Username format wrong (try with and without @domain.com)
Account locked or disabled

Solution: Double-check credentials, generate app-specific password if needed, or contact your provider.

No calendars found

If connection succeeds but no calendars appear:

Make sure you have at least one calendar in your account
Check that the calendars aren't hidden or archived
Try creating a test calendar in your provider's web interface
Some CalDAV servers require specific principal URLs (contact support)

Sync is slow

CalDAV calendars sync every 15 minutes, which is slower than Google/Microsoft:

This is normal due to CalDAV protocol limitations
No real-time push notifications available
Polling frequency balances responsiveness with server load

Need faster sync? Consider using Google Calendar or Microsoft 365, which support real-time webhooks.

Next Steps

Connect Another Calendar

Connect a second calendar to start syncing events.

Create a Sync Rule

Set up synchronization between your calendars.

CalDAV Protocol (RFC 4791)

SyncMyDay implements the CalDAV standard using:

PROPFIND: Discovering calendars and calendar collections
REPORT: Querying calendar data (calendar-query)
GET: Fetching individual calendar objects (iCalendar format)
PUT: Creating and updating events
DELETE: Removing events

Service Discovery

We use WebDAV service discovery to find calendar collections:

Perform PROPFIND on the provided URL
Look for calendar-home-set property
Query the home set for calendar collections
Present available calendars to user

Authentication

Basic Auth: Standard HTTP Basic Authentication over HTTPS
Digest Auth: Supported if server requires it
Credentials are encrypted at rest with AES-256

Polling Strategy

Since CalDAV doesn't support push notifications:

Poll every 15 minutes for changes
Use getctag (collection tag) to detect changes efficiently
Only fetch changed events using getetag
Minimize bandwidth and server load

iCalendar Format

Events are exchanged in RFC 5545 iCalendar format:

Parse VEVENT components
Extract DTSTART, DTEND, STATUS
Handle recurrence rules (RRULE)
Support timezone conversion (VTIMEZONE)

Known Limitations

No real-time sync: 15-minute polling interval
Server dependencies: Requires proper CalDAV implementation
Firewall restrictions: Server must be internet-accessible