AI Detectors.io vs ContentDetector.org

AI Detectors.io analyzes text associated with major language models, returning an overall AI probability, confidence scores, and sentence-level results. The site also offers a humanizer, citation verification, plagiarism checking, grammar tools, and watermark removal. Its detector says it examines perplexity, burstiness, n-gram patterns, and stylometric fingerprints. The company reports 95.2% accuracy and 3.1% false positives from an April 2026 benchmark of 500 texts. The detector is trained and benchmarked on English; it returns scores for other languages, but those languages are outside that benchmark. Access is available through the web, Chrome extension, Microsoft Word add-in, and REST API. The Word add-in supports Word 2016 and later on Windows and Mac, as well as Word for the web, and can produce PDF reports. The free plan includes 10,000 words per month and a 500-word-per-use limit. Premium is listed at $8.33 a month, billed annually, with scans up to 25,000 words. Submitted text may be processed by third-party providers and retained as long as needed to support the service.

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.