Bookmarks Clean Up - Find and remove duplicated bookmarks manually and in batches, get rid of broken bookmark links and empty folders.
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
syncmarx - A simple Web Extension for synchronizing bookmarks between browsers.
Firefox Sync - Bring your Firefox bookmarks, tabs, or passwords wherever you go with Firefox Sync. Share between computers and mobile devices. Get Firefox now!
xBrowserSync - Free and open source tool for syncing your bookmarks and browser data between your various browsers and devices.