When I moved to using Safari as my default browser I found my bookmarks it had imported were in major need of cleanup… tons of duplicates,dead URL, etc. I have been doing them manually for the last day or so… or at least until i found AM-DeadLink.
AM-DeadLink detects dead links and duplicates in browser bookmarks and text files. If a bookmark has become unavailable you can verify and delete it permanently. Additionally you can download Favicons for all your Favorites and Bookmarks.
The best part is: AM-DeadLink is freeware!
Check out AM-DeadLink