This document discusses various plagiarism detection software tools, including Turnitin, Urkund, and other open source options. It provides brief overviews of 15 popular plagiarism checking tools, focusing on their key features. The tools discussed can check documents for duplicated or copied content, often scanning billions of web pages. They generate originality reports and identify sources of non-original content to varying degrees of precision and language support. Many are available for free or at low costs.