It is difficult enough tracking down relevant and useful sites, but keeping up with changes to the pages is an impossible task when you have more than a dozen or so to monitor. Link checkers such as Xenu Link Sleuth (http://home.snafu.de/tilman/xenulink.html) can alert you to pages that have disappeared or that are redirecting users to another site, but changes to the content are equally if not more important.
There are many services that track web page content for changes. Some are free whilst other priced services may offer limited facilities as a free taster.
This overview looks at two types of services: web based services and software programs for PCs and Intranets.
Web based services
This is a free service allowing you to track an unlimited number of pages. The frequency of the alerts can be daily, weekly or monthly and you can choose to only have alerts for "sizeable changes", when content has been added or removed, or for specific keywords. The email merely alerts you to the fact that there have been changes; you have to click on a link in the email to view them in the Change Detection web site. RSS as well as email alerts avialable.
This service allows you to have up to 3 "trackers" with 30 checks per month free of charge. There is a Solo (Eur 1.20/month or Eur 12/year) and a Premium plan (Eur 3.50/month or Eur 36/year) that allow more trackers and additional options (see http://femtoo.com/pricing/). You can select the content to be tracked and how it is to be treated (text or numerical). Alerts can be delivered by email, Pushover (notification service for iPhone and Android) and a personal Tracker RSS Feed.
The free service provides 20 daily checks and 1 hourly check per user. You can track additions, deletions, Google page rank, keywords, and sections of a page. Alerts are sent to you by email. The Pro account gives you 1000 daily checks, 20 hourly checks, 5 10-minute checks and 100 weekly checks.
The free trial tracks up to 10 pages free of charge for 30 days and allows you to associate categories and descriptions with a "minder". Within the advanced options you can specify how often, in days, the page is to be checked. The most frequent check allowed for free is every 1 day. You can also specify the minimum number of changes that must occur before you are notified and any keywords or phrases that must appear in the changes.
Infominder Professional costs USD 30/yr to track 100 pages, USD 60/yr for 250 pages, USD 120/yr for 500 pages and USD 250 /yr for 1000 pages.
Infominder Premium allows you to monitor changes up to 4 times a day and costs USD 65/yr for 100 pages, USD 125/yr for 250 pages, USD 300/yr for 500 pages and USD 500/yr for 1000 pages.
Page2RSS tracks web pages for changes and notifies you of those changes by RSS. Simply type in the URL of the page you wish to track and then add the feed URL to your favourite feed reader. Excellent tool for pages that do not offer their own RSS feeds.
This web based tracking service allows you to compare versions of web pages side by side. Changes are colour coded so that you can see what has been added, deleted or modified. It also monitors changes to the HTML source code of the page. You can set up email alerts to notify when changes to a page have been identified. The different versions of the web pages you are tracking are stored for a year and can be viewed chronologically. There is a calendar view so that you can see how a page has changed over time and how many changes have occurred on a graph so you can see on which days the changes occurred. There are three pricing plans: Basic (USD 49.99, Premium (USD 79.99) and Ultimate (USD 99.99). The plans differ in the tracking frequency - weekly, daily, three times daily- and the number of URLs that you can track.
Watch That Page
This is a free service run by ATS Consulting, a Norwegian company that specialises in software development. You can track an unlimited number of pages, which can be grouped into folders and tracked on a daily or weekly basis. There is a keyword matching option that filters the changes that are relevant to you, for example if you are only looking for news where a certain term or phrase occurs such as a company or a product name. Channels enable you to divide your pages into groups based on importance or content type. Each channel can have different properties: some can have keyword matching and daily reports whilst others can be checked less frequently and report all changes. Email alerts can include the text that has changed on your pages or just list the URLs of pages that have changed. If you are a professional or heavy user, you are required to pay a fee. Watchthatpage will notify you by email if you fall into the heavy user category.
Websnitcher is a free service that checks your pages every 3 hours and gives you a detailed list of changed textareas. Email notifications are sent once a day and it also generates RSS feeds from the collected data. It alerts you only to what it considers are relevant changes; the intelligent filter tries to ignore changes in date and what it considers to be irrelevant textareas such as how many users are online.
Copernic Tracker is a tracking program that costs US $29.95 (there is a 30 day free trial). Once installed on your PC it enables you to track any number of pages on external sites and intranets. You can track changed words, new links or images. There is a useful advanced query form for tracking specific words within pages, Boolean and other search operators (AND, OR, NEAR).
Copies of page revisions are stored locally so that you can compare changes that occurred in the past and add your own notes for tracked pages and each of their revisions. There are four pre-set tracking schedules: Multiple Times per Day, On a Daily Basis, On a Weekly Basis and On a Monthly Basis. Alerts can be a tray icon, desktop alert, SMS notification or email report with the tracked page contents and changes highlighted.
As well as general changes to a page you can track the page for the appearance or deletion of specified text, or track selected areas of the page. You can view changes from within the program or in your browser and be alerted via email, a pop-up on your desktop or a sound. The default checking frequency - minutes, hours or days - can be changed as can the frequency for individual pages. Price: 29.95 USD. 30 day free trial.
Page Monitor for Chrome
This extension sits in the background monitoring changes to the pages you have specified. Go to a page you would like to monitor, click on the Page Monitor icon and select "Monitor This Page". You can change how often the page is checked, specify how you want to be alerted to changes (sound, desktop notifications) and select specific parts of a page to monitor. Changes since the last check are highlighted.
UpdatePatrol checks pages for changes as often as you like and you can monitor single pages or entire web sites. It costs US $69.95 for a standard license and US $129.95 for the pro version. See http://www.updatepatrol.com/editions.html for details of the features supported by each edition. A free trial is available.
Note:UpdatePatrol is no longer being developed and is sold "as-is" in response to requests from customers and trial users.
Update Scannner for Firefox
A free add-on for Firefox. To monitor a page, display it in Firefox and from the right click menu select Scan Page for Update. You can select how often each page is to be scanned (from 5 minutes to once a week), whether or not to ignore numbers, and if insignificant changes are to be ignored (specify the number of characters from less than 10 to less than 1000 characters). An alert will pop-up at the bottom of the screen when changes are detected. Click the blue up-arrow on the bottom status bar to display the Update Scanner sidebar and pages that have been updated are shown in bold. Changes to pages are highlighted automatically.
The full version of this software is available on a 30 day free trial. It tracks an unlimited number of pages and you can choose to ignore HTML tags, images/banners, numbers and dates. You can enter user names and passwords for password protected pages that you wish to track. Pages can be checked once a day, once a week, or on a specified day or days of the week. You can even specify the checking frequency during a day either in hours or minutes.
You can track entire sites without having to specify each page individually (not available in the Basic Edition). As well as web pages you can track RSS and Atom feeds, but this feature is not really a replacement for a fully fledged RSS reader if you are a serious news junkie.
Prices are 29.95 Euros for the Basic Edition, 49.95 for the Personal Edition, 99 Euros for a single user Business licence, 1990 Euros for a site license and 9990 Euros for an enterprise licence.