Tips to keep track of changes of web page contents

Follow That Page

Register to start using Follow That Page, then click on Your Pages to add a new page to monitor. The settings for this service is quite simple. You can set the frequency of checks from up to 20 pages daily or every hourly for only 1 page. .The settings also allow you to receive site errors notifications like when it encounters a “Page Not Found” during a check.
AlertBox (Firefox)

For Firefox users, there’s a similar add-on called AlertBox. After installing AlertBox, go to the site you want to monitor and click on the AlertBox button at the end of your Firefox address bar. With AlertBox you can choose specific areas to monitor, by selecting it with your mouse. It highlights boxes of content by selecting the HTML div.
Page Monitor (Chrome)

Page Monitor is a Chrome extension that will monitor pages you want, and notify you of any changes to site. The Page Monitor button at the end of your Chrome address bar will have a number on it to signify that there’s a new notification.In the options, you can also set the intervals from as short as every 5 seconds to once every 2 days. There is also the option to enable desktop notifications with a sound alert that will remain on your desktop until you remove it.
VisualPing

VisualPing is easy to use and requires no registration. All you have to do is go to the site, type in the website you want to track and provide an email they can send notifications to. These notifications can be set to come in hourly, daily, weekly or monthly.There’s also a trigger option to get notifications for tiny, medium or major changes. Based on your settings, VisualPing will send you two images – a before and an after – to show how the site you are tracking has changed.
Versionista

Versionista requires an account to begin monitoring web pages. Once you add a page you want to monitor, it’ll scan the pages within the site. You can disable that if you only want to focus on a single page or on the the home page by unchecking “Look for more URLs”.Pages you monitor are checked automatically, once a day, otherwise you can access Versionista to manually check. If changes are found, you can compare it with an earlier version, up to 4 versions are saved before it starts overwriting.