This article compares plagiarism detection systems according to the list of criteria, compiled from the most challenging and important features for users in Ukrainian higher educational institutions. In addition it describes types of text-based plagiarism and provides an overview of the most common and serious forms of plagiarism around the world and in Ukraine in particular.The authors carried out a comparative analysis of three plagiarism detection systems − Turnitin, Unicheck, eTXT − and highlighted advantages and disadvantages of each one for the use in Ukraine. However, in further studies there might be a need for revising and expanding the list of criteria depending on the subject and the aim of using plagiarism checkers.