Top plagiarism detection tools are platforms that scan documents against online sources, research papers, and databases to identify copied or unoriginal content, helping maintain academic and professional integrity; tools like Turnitin, Copyscape, Grammarly, Copyleaks, and iThenticate differ in database size, AI detection, reporting accuracy, and ease of use, as Turnitin dominates academic institutions while Grammarly focuses on writers and professionals, so you should choose the top tool based on whether you need academic verification or general content checking.