No user interface, no instructions, absolutely nothing to guide use of this extension, rendering it useless. I'd like to know how those users who are giving high ratings managed to use this.

To launch: in "Extensions" (puzzle icon). Does what it is designed for

This extension has no instructions and no intuitive interface; in fact it has no interface or way to execute it at all.

No controls: no menu add-ons, no rh-click context sensitive button, nothing. It might work well if only I could figure out how to run it...

This Addon is awesome! Does exactly what is needed and possible, I was looking for something like this and its actually there!

I am quite shocked how many of my bookmarks are offline... like the web was dying.

Also very useful on TorBrowser to see if onion sites are down.

Still works!

404 Search should:
- note URL of bad bookmark in list generted
-search following order in the Bookmark tree in Firefox ...subfolder path should be shown

- bookmark title should be searched for within site as sometimes things are still there but located differently
-bookmark should be searched in Google (or other search engine) as it can sometimes still be found
-a csv list that can export bookmark name/URL/Path in Bookmark tree/Date added etc. would be helpful

The additional search features noted above could be run after the initial list is generated if this makes doing this easier

Does its main purpose quite well (tested on FF 56), but the addon is pretty much bare bones. No settings or options, no pause, no filters... a shame.

Excellent program. Easy to use, quick, highly recommended.

I use this every few months to efficiently cleanup my busy bookmarks folder.

特别实用的功能，有效帮我筛出失效书签，要是能显示我的中文分类名称就更好了。

Simple, worked well.

Não funciona na versao 68.1 (última pré-autosabotagem da mozilla) ou 80 do firefox mobile para Android mas funciona perfeitamente no PC.

That's so awesome I wish I had money to throw at you guys!

I installed this in Android Firefox I disabled all my other add-ons and this 404 bookmarks did nothing. No results. nada

Works as advertised!

This app needs options to slow it down and to pause the search. its causing my browser to crash and not allowing me to use google due to my email bookmarks activity!