GPTZero

GPTZero is a web-based AI content detector for content creators, educators, researchers, and teams that want to check whether text appears human-written or AI-generated.

Key capabilities include:

• Paste, type, or upload files (DOC, PDF, TXT) and run a “Detect Origin” check (up to 1200 words in the on-page editor).
• Detection for content generated by major LLMs including ChatGPT, GPT-4, Gemini, LLaMA, and others.
• Sentence-by-sentence analysis with sentiment analysis to help review which parts look AI-generated.
• Language options shown for English and French.

Pricing: Free Plan: 3,000 characters per scan, Document Scan, but no AI Plagiarism detection. Pro Plan: $4.99/month — 10,000 characters per scan, Document Scan, AI Plagiarism detection, no advertisements, and full Pro membership.

What makes it notable: it combines text and file upload checking with sentence-level breakdown, and the site positions it as usable without free-tier limitations compared with some other AI detector tools.