DETECT CHATGPT · GPT-4 · CLAUDE · AI WRITING · SENTENCE ANALYSIS
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AI CONTENT PROBABILITY
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WORDS
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SENTENCES
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AI SENTENCES
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HUMAN SENTS
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🎨 SENTENCE-LEVEL ANALYSIS
Likely AI
Mixed / Uncertain
Likely Human
⚠️ AI detection is probabilistic, not definitive. Results are based on statistical patterns and may produce false positives or negatives. Use as a reference tool only, not as conclusive evidence.
Free AI Text Detector – Check If Content Was Written by AI
By RapidTool Team · Last updated: September 2026
Our free AI text detector analyzes text for patterns commonly found in AI-generated content from tools like ChatGPT, GPT-4, Claude, Gemini, and other large language models. It evaluates multiple signals including sentence regularity, vocabulary uniformity, transition word density, and statistical patterns to estimate the probability that text was AI-generated.
How AI Detection Works
AI language models tend to produce text with specific statistical characteristics that differ from human writing. Our detector analyzes six key signals:
PerplexityAI text tends to use more predictable, lower-perplexity word choices
BurstinessHuman writing varies more in sentence length and complexity
Pattern UniformityAI often produces more uniform sentence structures
Vocabulary RichnessAI frequently uses formal, wide-ranging but predictable vocabulary
Sentence RegularityAI sentences tend to be more consistent in length and rhythm
Transition DensityAI overuses transition phrases like "furthermore", "moreover", "additionally"
Limitations of AI Detection
No AI detector is 100% accurate. Human-edited AI content may score lower (more human-like). Highly formal or academic human writing may score higher (more AI-like). Detection accuracy improves significantly with longer texts — use at least 200 words for reliable results.
Frequently Asked Questions
Can this tool detect ChatGPT-written content?
Our detector identifies statistical patterns common in ChatGPT and other LLM outputs — including unusually uniform sentence lengths, heavy use of transitional phrases, and predictable vocabulary. It cannot guarantee detection of every AI-written text, especially when the output has been edited by a human. Use it as a helpful signal, not a definitive verdict.
Why might human text be flagged as AI-generated?
Formal academic writing, legal documents, and technical documentation often share characteristics with AI text — structured sentences, consistent vocabulary, and heavy use of transition words. This can cause false positives. Similarly, creative or casual human writing typically scores much lower in AI probability.
How much text is needed for accurate detection?
We recommend a minimum of 150–200 words for meaningful analysis. Short texts don't provide enough statistical signal to distinguish AI from human writing. For best results, use 300+ words. The detector is most accurate with complete paragraphs rather than bullet points or lists.
Can AI detection tools be fooled?
Yes. "AI humanizers" and prompt engineering techniques can reduce AI detection scores by adding variation to sentence structure and vocabulary. Conversely, heavy editing of AI output can make it score as human. No detection tool is a replacement for careful human review of submitted content.
Is this tool useful for teachers and educators?
Yes, this tool can help educators flag potentially AI-generated submissions for further review. However, it should never be used as the sole basis for academic penalties. AI detection should be one part of a broader academic integrity strategy that includes assignment design, oral examinations, and writing process evaluation.