Bookmark Sentry is a Google Chrome extension that can scan all your bookmarks for duplicate and dead links.
Upon installation the extensions starts scanning in the background and finds problems such as connection errors, 404 errors, and more. The time taken for the scan depends upon the number of bookmarks you have and your folder structure.
Once the scan is complete, a report is displayed if it finds something.
Here, you then have the option of deleting them from your browser with a single click or you can first verify the link.
The extension runs a scan every month but can be adjusted for a different interval.
Download: Bookmark Sentry