Best AI Detectors 2025: GPTZero, Originality.ai & Winston

In 2025 the leading AI detector tools are GPTZero, Originality.ai, Winston AI, and Copyleaks. GPTZero excels in academic use with sentence-by-sentence AI detection and a low false-positive rate, now updated to detect outputs from GPT-4.1 and Gemini 2.5. Originality.ai targets content marketers and SEO teams, pairing AI detector functions with plagiarism checks, readability scores, and a full-site scanner. Winston AI delivers 99.98% detection accuracy, OCR for text in images, and integrations with Google Classroom and WordPress. Copyleaks serves enterprises and universities with multi-language paraphrase detection and enterprise-grade API access. No AI detector achieves perfect accuracy; performance varies by text length, topic, and style. Best practice is to cross-check AI detector reports and apply human judgment, especially for critical academic or professional content.