無料AI 盗作チェッカー

GPTINF's Plagiarism Checker compares your text against a database of over 70 billion active web pages and more than 150 million academic journals and papers, then returns an originality percentage along with any matching phrases it finds. Paste or upload your content, run a scan, and you'll see a clear breakdown of matches found, the percentage each match represents, and a direct link to the source so you can inspect the context yourself.

A match does not automatically mean something is wrong. Common phrases, properly quoted material, and correctly cited sources will sometimes surface as matches, which is exactly why the tool shows you the source link instead of just a raw score. Use a flagged match as a prompt to check whether the wording needs quotation marks, a citation, or a rewrite to make it clearly your own — the goal is protecting the originality of your final work, not chasing a perfect percentage at the expense of accurate attribution.

Plagiarism checking answers a different question than AI detection: it looks for text that matches existing published sources, while an AI detector estimates whether wording resembles machine-generated patterns. For research papers, essays, and published articles, it is worth running both the Plagiarism Checker and the AI Detector before submission, then using the Paraphrasing Tool or Grammar Checker to clean up any sections you decide to rewrite.