 Online dictionaries are increasingly becoming more popular as a tool for learning a foreign language. They provide users with a variety of features such as machine translation, multilingualism, video of pronunciation, images of words, discussion, collaboration, ranking of words, hints, and many other helpful tools. This paper compared the most popular online dictionaries and identified their key features. It also provided a comprehensive list of the additional tools available on each platform. This article was authored by Andrei V. Pekilnyak, Nadia M. Stetsenko, Volodymyr P. Stetsenko, and others.