SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Visualping - Visualping is the easiest to use website checker, webpage change monitoring, website change detector and website change alert software of the web. Read more about Visualping.
Sitechecker - All-in-one SEO platform including rank tracker, website SEO audit tool and website changes monitoring. Detailed reports by 100+ parameters with how-to-fix guides.
Distill Web Monitor - Distill is a web monitoring tool. It can monitor RSS feeds, a webpage or a part of webpage. Alerts in the form of pop-up, audio or emails can be received.
SEO Site Checkup - Find comprehensive search engine optimization (SEO) tools for your site.
Update Scanner - Update Scanner is a Firefox extension to monitor web pages for updates.