This article discusses the main age-related features of the Internet use by adolescents and children. Today more and more computers are connected to the Internet. At the same time, connection via high-speed channels is becoming more common, both at work and at home. More and more children get the opportunity to work on the Internet. But at the same time, the problem of ensuring the safety of children on the Internet is becoming more acute. For this, a security monitor was developed, which has many functions that allow you to use the Internet more safely and under parental control. This security monitor is written in the web programming language JavaScript and PHP, which will allow using the system on almost all modern browsers and on any computer. The article also provides screenshots of the program's operation and a flowchart with a detailed description.