AM-DeadLink
AM-Deadlink detects the dead links and duplicates, and marks them for removal. It can also clean up duplicates in comma-separated and tab-limited text files and saved URL files.
Checks your bookmarks are valid and the pages still exist, checks for duplicates and for empty folders and can restore missing favicons. Also checks and compacts (vacuums) your Places database.
Checks your bookmarks are valid and the pages still exist, checks for duplicates and for empty folders and can restore missing favicons. Also checks and compacts (vacuums) your Places database.
firefox-extension Discontinued duplicate-bookmarks