BEWARE: This add-on DOES NOT copy tags when it replaces a redirected URL. If you have tags and value them do NOT use this to replace redirects. Destroying your data is unforgivable.

Also this has obviously not been used or tested on a large number of bookmarks (I have over 2000) and it is a usability nightmare for two main reasons.
First, there is no way to select multiple URLS and apply a single action (remove duplicate or change a redirect).
Second, there is no way to use the keyboard to navigate or interact with the dialogs so you are forced to move and click with the mouse.

I AM aware there is a "Change ALL redirects" but this is dangerous e.g. many websites redirect to a login screen when you are logged out so now all your bookmarks for those sites would be for the login screen. Once again you need to adress these one-bu-one which I DID do only to discover my tag data deleted.

Works badly enough to be unuseable.

Finds as "broken" perfectly working, recent, fast bookmarks, so you have to check one by one everything it finds.

Does not say why the link has an error. Eg. if it doesn't answer, is broken (404), has an authentication error (which can be OK since you are not logged on), etc. so the results are useless.

It is not possible to mass-delete a group of bookmarks anyway.

Quite slow altogether, even with a 1Gb link it's slow.

Doesn't cache the results even for a little time so if you inavertendly close the result windows while checking for actually broken links, you must start over again.

Can't stop a running task, so if you started over again and find it too long, you can't cancel it to search for something else.

Can't choose where to start or which folder to check, it's all or nothing.

Won't remove obsolete separation lines, so if you deleted a number of bookmarks you get a collection of useless separation lines in the folder.

Will do nothing to actually "organize" your bookmarks, the name is misleading.

You cannot whitelist a folder.

Bye bye.

Katastrophe: Sah nach einem zweiten Durchlauf alle meine Lesezeichen als Fehler an und löschte sämtliche. Tipp: vorher Lesezeichenbackup machen!

Every DELETE must be confirmed -- if there are hundreds, just annoyng

The scan feature is extremely fast, the fastest from the extensions I've used of this nature thus far. However, the lack of a delete all or a checkbox system to make that part of the process faster makes this utterly useless unless you only have a handful of bookmarks. At which point, you could do everything this extension does manually anyway. To make matters, better or worse, when deleting a bookmark you have to manually confirm its deletion.

I don't know about other users, but the reason I need an extension like this is because my bookmarks are in the 10,000 range (actually used to be more like 50,000 but it got better). Because of this, not only is it important that the scan feature is reliable and relatively quick, but the ease of what comes next is also important.

Got stuck after having analysed all my bookmarks for several hours.

Finds fairly well all errors and duplicates but it's simply horrible trying to delete all of them. Uninstalling fro FF

Developer: "I think I'll automate the collection of information, but make actually doing anything with it as hard as possible!"

You can't even tab to the button you want to push on the popup.

Windows 3 had a better UI than this.

Seems almost deliberately slow and tedious, like the developer thinks we want to sit and manually remove 1,000 duplicates one at a time.

it finds the duplicates but has no button to delete them..

I know I've got a lot of bookmarks, but it is supposed to help me get rid of the dead ones and duplicates, so that is exactly what I want it to do.

But Firefox always crashes after about 4,000 are checked, 2,700 warnings and 300 errors.

So why, Mr Developer, don't you add the ability to select which folder of bookmarks to check? Or specify a number of bookmarks to check and then stop, so we can deal with some of the checked bookmarks before it crashes Firefox?

...just an idea.

Dopo aver cancellato molti bm segnalati come errati, mi sono accorto che invece erano ancora attivi. e non ci sono altre funzionalità...

Looks like extension doesn't work

This add-on takes over your cookies settings without telling you. Depending on how many bookmarks you have, this add-on might also freeze your browser for more than a few seconds.

First it needs to scan, then, in the results not shows the full path of bookmark(s) but it shows them at second scan, then, you have to delete unneeded bookmarks one by one(!), then, I needed to refresh (scan again) and then not working, It freezes.

Not working

Impossible de l'installer. Message : l'extension est corompue

As others have written, this extension has problems. The biggest are that while it might identify duplicates, it does not offer a way to select duplications for deletion. This might be fine if one had a few duplicates. It quite another thing if one has hundreds or more duplicates.

Second, the extension supposedly identifies broken links. However in spot checking some of these links, I find they are working.

Lastly, if one has thousands of bookmarks, this program will consume lots of memory. You mostly likely will get Firefox or even Windows to have problems.