Marker is described as 'Simple Online Bookmarking. Marker is designed to make saving, organizing, and sharing your bookmarks simple. Because they are stored in the cloud, all of your saved links are available from any device'. There are seven alternatives to Marker, not only websites but also apps for Mac and Google Chrome. The best alternative is Pinboard. It's not free, so if you're looking for a free alternative, you could try Bort or Draggo. Other great sites and apps similar to Marker are LinkLocker (Paid), BookMacster (Paid), URL Manager Pro (Paid) and TeamSync Bookmarks (Freemium).
Pinboard is a bookmarking website intended for people who want to reliably keep track of large numbers of links. Its goals are to be useful, fight bloat, keep things fast, and stay small. Social bookmarking for introverts. m.pinboard.in
TeamSync Bookmarks enables users to share and mange bookmarks across a team or friends in real-time. Share, manage, and sync anything with a URL in group folders that you create. Then, invite friends, family, coworkers, or teammates to your shared bookmark.