ContentDetector.org vs Detecting-AI.com

ContentDetector.org is a free tool that estimates whether text was AI-written and reports a percentage split between AI-written and human-written content. Users can paste text, upload a file, or submit a URL for a report with a score, section highlights, and review guidance. The site says the detector evaluates token-pattern predictability, semantic repetition, formatting regularity, and local stretches of uniform phrasing, including patterns associated with GPT-5, Gemini, Claude, and other large models. It also offers a converter that rewrites AI-generated text to improve tone, flow, clarity, and sentence variety; the converter page shows a 1000-character input counter. Other listed options include API access and bulk checks of folders or URL lists. Platforms include web, extension, iOS, macOS, and Windows. The site says inputs are not used to train models and describes retention controls; its FAQ says inputs are removed when the tab is closed, while the converter page says submitted content is processed instantly and not stored. It warns results can be wrong, especially for very short or heavily edited text, and recommends human review.

Detecting-AI.com analyzes writing for signals associated with AI-generated text and presents a document score with highlighted passages. The web detector accepts pasted text plus TXT, PDF, and DOCX files; scanned PDFs requiring OCR are not supported. It is designed for text linked to GPT, Claude, and Gemini, including edited or AI-assisted drafts. The service preserves document structure, scores eligible sentences separately, and combines those scores into a document signal. The maker reports 99% detection accuracy and a false-positive rate under 1% on its described datasets, while noting that short, translated, heavily edited, or formulaic writing can be harder to classify and that a score cannot establish authorship or misconduct. Paid plans add unlimited AI detection, an AI Humanizer, Fact Checker, and plagiarism credits. REST APIs cover detection, humanization, and plagiarism checks, with a remote MCP server for compatible assistants. The free plan requires no account and allows 15,000 characters per check. Paid pricing starts at $7 a month billed annually.