It's a really good foundation! I especially like the broken link feature.

It can be the best tool on the market if these functions are added:
- Check all / Uncheck all
- Filter bookmarks via site/search
- Organize bookmarks by URL / Name / Broken / folders
- Mass delete Bookmarks / broken links
- Filter names / folders via a search box with alternative for if the search is for names / folders
- Disable the warning of deleting a bookmark

...because deleting 100 bookmarks one by one takes a long time, especially wit the warning box

Extra:
- Save search for broken links (same folder as the last scan for broken links)

Copy some of the features of "Bookmark Dupes". Bookmark Cleaner Pro - Duplicate Remover & Manager + Bookmark Dupes makes more of the job done.

Summary: It's a great foundation and will be a 5/5 when it's more customizable.