Plag is a web-based plagiarism checker and AI detector aimed squarely at academic writing. You upload a document, and rather than returning a single opaque percentage, it breaks the result into parts: an overall similarity score, a separate plagiarism risk indicator, the proportion of paraphrased material, the proportion of improper citations and the highest match from any single source. That structure is what makes the report actionable, because each category points to a different fix.
The interface reinforces this. Paraphrased passages are flagged in orange, improper references in purple and correctly formatted quotations in green, so a student can scan the document and understand which passages actually need work. Every flagged section carries a link to the matching source, which lets you confirm the overlap and correct the citation or rewrite the sentence with the original context in front of you. Plag presents itself as one of the few checkers that surfaces improper citations as a distinct category rather than lumping them in with outright copying.
The comparison base combines open web sources with a scholarly article collection of more than 80 million items from recognised academic publishers. Plag also advertises real-time search that can detect similarities with pages published as recently as roughly ten minutes earlier, which matters when students draw on fresh blog posts, news pieces or documentation. The tool supports 129 languages, matching its multilingual user base in Europe and beyond.
On the commercial side, Plag keeps a free entry point: an initial check with a similarity score, available before you commit to a paid report, and free educational use for teachers, lecturers and professors at schools and universities worldwide. Paid plans and document services such as editing, proofreading, formatting and plagiarism removal are available for students and institutions.
