I use this handy addon to get rid of all unwanted bookmarks.
Will be hepful if various error codes are handled in different sections.
also many urls with network error are working, maybe you should wait before requesting new outgoing connections ?

I like the idea of it, however, when dealing with several 1,000 bookmarks and lets say a 1,000 are a mixture of 404 or possible 404 its to time consuming to individually select each one so not to include the possible 404.

Maybe group them better (e.g. redirects, timeouts, resource not found, unspecified 40x/50x, server not found, etc.). Allow one to check mark one box scroll down holding shift and click further down and will select everything in that range.

UPDATE 20190911: I decided to start with a fresh profile. In it is a total of 9 bookmarks; 5 of which are the default bookmark preloaded the other are 4 I added. When I run 404 nothing comes back under expired or other which is correct. However, I noticed it reports only 4 unexpired bookmarks rather than 9. So is it intentional to exclude the preloaded bookmarks? NOTE: No Adblockers or any other extension other than 404.

Efficient in finding the dead links, but while doing so, it produces extreme traffic that sends my ISP into red alert and into bugging me with recaptcha checks. Meanwhile, Firefox comes to a halt and crashes from overload. The hit list is not saveable, so there is no other way about it than starting all over again, and going into an into an endless feedback loop. Sadly, I have to uninstall it, though I have no functional replacement for it.

Facile à utiliser et fait le job.

Пользоваться приложением неудобно, потому что нет индикации его работы, и доли сделанного от всего объема запланированных для проверки закладок. Кроме того, отображается название закладки, но не отображается ни путь к ней, ни ее адрес.

Very fast checker for 404 and other types of book marks, and very easy to remove ones that are no longer valid.

Works great for me!

Great - does everything it says. Pretty straightforward, no instructions necessary! One thing I would like to see is the location of the flagged bookmarks. I have one that, when I click it, sure it's a 404, but going up one level takes me to a good website, so I'd like to keep and edit that bookmark - but I can't find it! lol I have too many bookmarks and that was the main reason for getting this extension. But searching through my bookmarks for this mystery link is a bit much, so it would be great if this extension would show me which subfolder it's in. Any chance of adding that feature?

Useful, but the add-on would be much better, if it was possible to check, if wayback machine has a version of the dead site and to replace the original link with the link to that stored version at wayback machine.

Easy decluttering for my tons of bookmarks. Awesome!

This is EXACTLY what I was looking for. Thanks!!