At the time of writing Xmarks, a bookmarks synchronizer between browsers and operating systems, is no more. 1st of May the service will stop.
You can sync your bookmarks to the cloud in Firefox and Chromium (or Google Chrome) but not in Vivaldi.
Vivaldi is working on a new release called in Arch Linux – vivaldi-snapshot. When we install that browser, we can create an account and are then able to sync our bookmarks to the cloud as well.