LinkLocker - LinkLocker is a lightweight bookmarking service with an emphasis on privacy.
Firefox Sync - Bring your Firefox bookmarks, tabs, or passwords wherever you go with Firefox Sync. Share between computers and mobile devices. Get Firefox now!
Bookmarks Clean Up - Find and remove duplicated bookmarks manually and in batches, get rid of broken bookmark links and empty folders.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
URL Manager Pro - URL Manager Pro for Mac OS, the most powerful bookmark manager for the Mac for use with Safari, Firefox and Chrome
Diigo - Diigo is a powerful research tool and a knowledge-sharing community