DF Site Monitor (C++) - is a system for monitoring web sites. The system allows monitoring the availability of web sites and their content by checking whether the given content exists or does not exist on the site. The system can be used autonomously or as a module for other systems. For acquaintance with system there is demo and trial version of system. There is a web interface for adjusting the system and watching the monitoring progress and site status. Simultaneous scanning of multiple sites. Multithreaded sites check. Several methods of user notification when a site changes its status (e-mail, command execution, GET). Search by masks. Masks enable you to analyze the HTML code in a deeper way. For instance, with masks you can figure out whether your link is in document body (), whether it is inside comments or not, and whether there are unclosed HTML tags in front of it which prevent its correct displaying (,