This would be 5 stars, but reducing the rating as time marches on. Development was abandoned 5 years ago. Over time more sites break and show blank pages. As Firefox moves away from open source, it's what you should expect.

Полностью бесплатное приложение с открытым исходным кодом. К сожалению, в дополнении нет возможность выделить интересующую область для отслеживания изменений - как это сделано в Distill Web Monitor и Otsledit. А на нынешних сайтах со множеством динамического контента и десятками независимых блоков без это функции пользоваться приложением тяжело. очень много ложных срабатываний. Из плюсов - отсутствие ограничений на количество подписок. В отличие от упомянутых выше продуктов.

It's a very usefull extension. But I don't understand why regulary all pages disapeared and I need to import again my pages...

youtube channels/pages fail to scan properly
www.pscp.tv/ScottAdamsSays gives javascript error

Pretty useless due to lack of proper changes threshold.

estou iniciando uso agora...?

My updates are not highlighted. How do I get them to be highlighted?

Can we export the Update Scanner settings?

Does this let you monitor web sites that need a password?.

I have been using this addon for a long time. I understand that ff changed its paradigm and so this addon had to as well. However, as other users have noted, it just kind of stopped working at all lately. I go to the site I have it check and there are major changes, but it always says no changes when run. I would love to give this five stars, but 3 for this current iteration, out of hope.

Works fine so far with Firefox Quantum (58.0.2) and AddOn version 4.2.0.
The problem:
you cannot delete a page from the UpdateScanner list, when you don't need a page to be longer in this list.
The page settings don't have any delete option :-(

Let us set 15/30/60/120 second intervals

This Is Fantastic! This Is Awesome! I'm a Sweeper and I enter over 600 Dailys, but I also need to monitor 1000s of sites for changes to find more sweeps to enter. So far I have tested with approximately 100 sites, waited 24 hours and sure enough-Update Scanner detected a change on every page. The affect on the browser resources is unnoticable, even though this is Firefox.

I highly recommend this add-on to everyone.

What I would like to see in future releases:
-Sorting
-Adding New items directly to Folders
-Duplicate detection
-Set Global Settingsas well as Individual Settings

***UPDATE***
I am receiving error messages or no textual content at all from
Active Server Pages(asp) when using Update Scanner. Examples include:
http://710wfnr.listenernetwork.com/asp2/usepoints.aspx?status=current
http://fans.wava.com/asp3/contests.aspx
http://nashfmwisconsin.listenernetwork.com/asp2/usepoints.aspx?status=current

OK, I believe in my extreme use I should expect a hit on resources and performance
to Firefox. So I now am requesting additional features:
-Run when the browser is idle
-A Pause option, instead of having to Disable

It was better before.

Now - unfortunately all time there are`nt two very important functions:
• Scan only the selected folders or pages
• Add new pages by dragging an address to the selected folder

I am waiting patiently for these functions.

Have used Update Scanner happily for many many years and have had problems getting to grips with this update. What a shame as it was a wonderful useful add-on to FF.

Not happy initially with the changes. At first, having imported all my Update Scanner Bookmarks, I had a sidebar showing over 200 items all saying 'New Page'. By uninstalling and reinstalling that seems to have been rectified. However, seem to have lost all identification of changes on pages that I hadn't reviewed. Now have to start all over again.

Disappointed to lose the option to right click and ask Update Scanner to scan a page.

Comparing the Update Scanner for FF57, as of 21Nov17, with its predecessor: I much prefer the old version. The new version opens sites in a page of its own, with a name like "moz-extension://f79626ca- etc. etc.". If you click on a link in the page it no longer works; on seeing a list of changed files, you can't click on any of them. This is a major issue for me.

It was convenient, with the sidebar opened, to click there to scan all pages. There may be ways round these issues, but they're not obvious. A nuisance, not major. I usually scan manually, setting the automatic scan to once weekly.

As many have commented, the scanner often reports pages to have been changed when there is no visible change; I expect that is unavoidable due to the nature of the pages, but is a nuisance.

On balance I still find the current version better than nothing; in particular I have a list of sites to remind me which to check. But it's got worse.

On ne peut plus lancer la mise à jour manuellement.
Si on surveille une page avec login (ex : forum), la page reste bloqué à la page d'identificattion.
Impossible de mettre à jour une page qui n'a pas déjà été scannée, je ne comprends plus du tout ce nouveau fonctionnement.
J'ai eu du mal à récupérer mes favoris mais c'est fait, ouf !
En tout cas, l'appli fait le minimum : surveiller les pages sans flux RSS, et cela me convient ^^