Synchronizing with Thunderbird
Thunderbird is a feature-rich and mature mail client that can be turned into a full-fledged Personal Information Manager (PIM). Since version 102, it supports address book synchronization via CardDAV and automatic discovery of calendars and address books available on the server.
Since Thunderbird 102, the CardDAV protocol is natively supported.
To enable it:
On the address book view, click the down arrow near "New Address Book" and choose "Add CardDAV Address Book".
In the next window, type your user name and URL of your server.
The next window will ask for your username and password for this account.
The previous window will be refreshed and ask you which address books you wish to sync.
Choose and then click Continue.
If you later want to add a new address book, you can redo all of those steps and only the books not already synchronized will be suggested.
For calendars, the CalDAV protocol is also natively supported.
To enable it:
Click on "+" near Agendas on the agendas page.
Choose "On the network" on the next window.
Type your "user name" and "Url of the server", then click on "Find Calendars".
Choose which agendas you want to add and click "Subscribe"
Same thing here, if you later want to add more calendars, just redo the procedure.
Alternative: Using the TbSync addon
For this method, you need to have two add-ons installed:
When they are installed, go to Extras/Synchronisation settings (TbSync) if you are on Windows, or Edit/Synchronisation settings (TbSync) if on Linux, then:
In the account manager choose "Add account / CalDAV / CardDAV account"
In the next window, go with the default called Automatic configuration and click next
Enter an account name (which you can freely choose), a user name, a password, the URL of your server, and click next
In the next window, TbSync should have auto-discovered the CalDAV and CardDAV addresses. When it has, click Finish
Check the Enable and synchronize this account box. TbSync will now discover all address books and calendars your account has access to on the server
Check the box next to each calendar and address book you want to have synchronized, set how often you want them to be synchronized, and push the button synchronize now
After the first successful synchronization is complete, you can close the window.
Henceforth, TbSync will do the work for you. You are done with the basic configuration and can skip the next sections unless you need a more advanced address book.
Alternative: Using the CardBook add-on (Contacts only)
CardBook is an advanced alternative to Thunderbird's address book, which supports CardDAV. You can have TbSync and CardBook installed in parallel.
Click the CardBook icon in the upper right corner of Thunderbird:
Go to Address book > New Address book Remote > Next
Select CardDAV, fill in the address of your Nextcloud server, your user name and password
Click on "Validate", click Next, then choose the name of the address book and click Next again:
When you are finished, CardBook synchronizes your address books. You can always trigger a synchroniZation manually by clicking "Synchronize" in the top left corner of CardBook:
The old method: Manually subscribing to calendars
This method is only needed if you don't want to install TBSync.
Go to your Nextcloud Calendar and click on the 3 dots menu for the calendar that you want to synchronize which will display an URL that looks something like this:
Go to the calendar view in Thunderbird and right-click in the calendar menu to the left (where the names of the calendars are) to add a New Calendar.
Choose On the Network:
Choose CalDAV and fill in the missing information: