Monitor Webpages for Changes
If you’re a Firefox user then you can try update scanner . It’s an extension that lets you monitor webpages for changes. You have an option to choose how often the website should be checked for changes, and whether it should ignore the minor ones, such as the changes to numbers.
When the page changes it shows a notification alert. If you monitor multiple webpages then you can get a quick overview of pages using the arrow button located at the right bottom corner of the screen. Web pages that have been updated will be shown in bold with an arrow next to them.
If you don’t use Firefox then you can try ChangeNotes or ChangeDetection. Both of these websites can monitor requested webpages and will send you an email when something changes.
Monitor Error Pages
Mr. Uptime is a bit different but serves a similar purpose. It’s another Firefox extension that comes in handy when you come across a website that’s experiencing down time. With Mr.Uptime you are able to add such a website to the watchlist and get notified as soon as the website is back online. The following image sums up the whole idea pretty well:
There is also an option to specify the interval at which the page should be monitored. Check out Mr. Uptime video screencast here.