PlagiarismCheck.org is an online plagiarism and AI detection tool that helps users verify text originality, detect AI-generated content, and improve writing quality. It uses advanced algorithms to compare submissions against extensive databases and real-time web searches, identifying exact matches, word substitutions, phrase rearrangements, and AI patterns. The tool provides interactive, downloadable reports with highlighted similarities and source links, supporting formats like DOC, DOCX, TXT, RTF, PDF, PPT, PPTX, and ODP. It distinguishes between plagiarism and properly cited quotations, and includes a built-in citation generator and grammar checker. Designed for educators, students, writers, and businesses, PlagiarismCheck.org integrates with major learning management systems such as Canvas, Moodle, Google Classroom, Schoology, Brightspace, Blackboard, and Populi, and offers an API for custom integrations. The tool ensures strict confidentiality and operates entirely online.