Smarky is the bookmarks manager for Safari bookmarks which is compatible with Apple's iCloud. After installing Smarky and enabling iCloud syncing, you can have automatically alphabetized and organized Safari bookmarks on all of your Apple devices.
Note: We are no longer actively promoting Smarky because, beginning with one of the Safari 11 releases, in Safari’s Bookmarks > Edit Bookmarks, there is a Sort By > contextual menu which will sort items. This is certainly not as powerful and flexible as Smarky, but given that installing and maintaining any app is a bit of work and cognitive overhead, we feel that users who just want their bookmarks in alpha-numeric order are better off by once in a while using this this new function which is now built into Safari. However, if you are a bookmark nerd that wants more, Smarky's built-in store is still open and our plans are to continue supporting Smarky.