Use a service with card DAV support like posteo.de.
My contacts are synced between an iPhone, Linux Mint and a Mac. My Parter syncs between an iPhone and a Windows PC (Witt Thunderbird as mail Client).
Submitted 6 months ago by CoderSupreme@programming.dev to [deleted]
I use fossify contacts, which allows you to read and write your contacts to/from a VCF file (as opposed to import/export which must be manually done, this keeps them in the file so as you add/remove contacts the file is updated) and synching to keep the VCF file synced between my devices. No servers of any of that maintenance overhead needed.
You can use synching for all kinds of stuff too. I sync calendar (with fossify calendar) and a keepass PW database and 2fa keys this way.
Well, I use NextCloud (via Nextcloud AIO) as my cloud backend for almost everything. If all you want is contact syncing, that is anlmost certainly overkill. It’s a Big project that does just about everything.
If I remember correctly, there were a few more focused project listed in the Awesome-Selfhosted repo that may be useful to you.
I hoy Baikal.myself and sync to it via davx5 on android and via Thunderbird in ubuntu
ptz@dubvee.org 6 months ago
I run a Nextcloud server and use DavX5 on my phone to sync my contacts and calendars over WebDAV. Works great.
If Nextcloud is more than you need, you might try Radicale which just does CalDAV and CardDAV.