A framework with support for HTML, CSS and JS is used by developers to build responsive web applications. Bootstrap is one of the most popular among similar platforms, a large number of sites have been created on it. In addition to high speed, the framework has versatility. It is cross-browser and cross-platform. For ease of use, there are many ready-made solutions and components. The design of the projects is homogeneous, each element is coordinated with each other. Bootstrap is constantly being updated and improved, so today it is not just a set of ready-made development tools, but a well thought out front-end framework.