AI Text Detector - Check If Text Was Written by AI

Paste any text to instantly detect if it was written by ChatGPT, Claude, Gemini, or other AI tools. Analyzes 5 statistical writing signals including burstiness, vocabulary, and predictability. 100% free, no signup, completely private.

AI Text Detector: Paste your text into the AI content detector above and click Analyze. It checks 5 writing signals — sentence burstiness, vocabulary richness, AI phrase predictability, repetition patterns, and stylistic markers — to score how likely the text was written by ChatGPT, Claude, Gemini, or other AI. Results are instant, free, and 100% private — your text never leaves your browser.

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Key Takeaways

Detects AI-written content from ChatGPT (GPT-4, GPT-4o), Claude, Gemini, Copilot, Jasper, and other LLMs
Uses 5 independent statistical writing signals for maximum detection accuracy
Analyzes burstiness, vocabulary richness, AI phrases, repetition, and stylistic patterns
Works on essays, articles, blog posts, emails, cover letters, and academic papers
Runs 100% in your browser — your text never leaves your device
Completely free with no signup, no limits, and no watermarks

What is AI Text Detector?

AI Text Detector — An AI text detector is a tool that analyzes writing patterns to determine whether content was generated by artificial intelligence — including ChatGPT (GPT-4, GPT-4o), Claude, Gemini, Copilot, Jasper, and other large language models — or written by a human. It examines statistical signals like sentence length variation (burstiness), vocabulary diversity (Type-Token Ratio), phrase predictability, structural repetition, and stylistic markers to produce a confidence score.

This free AI text detector uses multi-signal statistical analysis to determine whether text was written by a human or generated by AI tools like ChatGPT, GPT-4, GPT-4o, Claude 3.5, Gemini Pro, Microsoft Copilot, Jasper, Writesonic, or other large language models. Unlike server-based detectors like GPTZero, Originality.ai, or Turnitin, it runs 100% in your browser — your text is never uploaded, stored, or processed externally. The detector combines five independent analysis techniques: sentence burstiness (how much sentence lengths vary), vocabulary richness (Type-Token Ratio and hapax legomena), predictability analysis (50+ AI transition phrases and formulaic patterns), structural repetition detection (parallel phrasing and repeated patterns), and stylistic analysis (contraction rate, passive voice, hedging language, punctuation variety). Each technique catches different AI writing characteristics, and when multiple signals agree, detection confidence increases dramatically.

How to Use AI Text Detector

1
Paste or type the text you want to check for AI writing into the text area. Minimum 50 words, recommended 200+ words for best accuracy.
2
Click 'Analyze Text' to start the multi-signal statistical analysis.
3
Review the overall AI probability score and verdict (Likely Human, Uncertain, or Likely AI).
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Expand each of the 5 signal cards to see detailed sub-scores and exactly what was detected.
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Check the text statistics panel for word count, sentence count, Flesch-Kincaid reading level, and other metrics.

Key Features

AI Content Detection from All Major ModelsIdentifies text generated by ChatGPT (GPT-4, GPT-4o), Claude (3.5 Sonnet, Opus), Gemini (Pro, Ultra), Microsoft Copilot, Jasper, Writesonic, Copy.ai, and other large language models. All LLMs share similar statistical generation patterns that this multi-signal approach detects.

Sentence Burstiness AnalysisMeasures the coefficient of variation in sentence lengths, consecutive length differences, and monotone run detection. Human writing naturally alternates between short (3-8 word) and long (25-40+ word) sentences. AI models like ChatGPT produce uniformly medium-length sentences (15-25 words) with low burstiness — one of the strongest detection signals.

Vocabulary Richness DetectionCalculates Type-Token Ratio (unique words / total words), hapax legomena ratio (words used only once), and repeated bigram/trigram frequency. Human writers use more diverse vocabulary with higher rates of unique words. AI-generated text reuses common words more frequently and has fewer hapax legomena.

AI Phrase Predictability ScannerScans for 50+ common AI transition phrases including 'Furthermore', 'Additionally', 'It's worth noting', 'In conclusion', 'It's important to remember', and 'Let's dive in'. Also detects formulaic paragraph openers, low sentence-starter diversity, and template-like paragraph structures typical of ChatGPT and Claude output.

Structural Repetition AnalysisIdentifies parallel phrasing patterns, list-like structures, consecutive sentences starting with the same word, and repeated syntactic templates. AI models generate text with more structural regularity than human writers, who naturally vary their sentence construction.

Stylistic Pattern DetectionAnalyzes contraction rate (AI uses 'do not' instead of 'don't'), passive voice frequency, hedging language density ('arguably', 'it could be said'), punctuation variety, and first-person pronoun usage. AI-generated text tends toward formal, impersonal, and hedging-heavy writing styles compared to natural human expression.

Flesch-Kincaid Readability ScoringCalculates the reading grade level of the analyzed text. AI-generated content frequently clusters around grade 10-12, while human writing shows more variation depending on context, audience, and individual style.

Privacy-First DesignAll analysis runs 100% locally in your browser using pure JavaScript with zero external dependencies. Your text is never sent to any server, never stored in any database, and never processed by any API. This makes it safe for analyzing sensitive documents, student papers, confidential emails, and proprietary content.

Use Cases

Teachers and professors checking student essays and homework for AI-generated writing from ChatGPT or Claude

Editors and publishers verifying content originality and human authorship before publication

SEO professionals auditing blog posts and web content for AI-generated quality issues

Recruiters screening cover letters, writing samples, and job application essays

Researchers validating that survey responses and study participants wrote their own answers

Content managers checking freelancer and contractor submissions for undisclosed AI usage

Students self-checking their own writing before submission to avoid false positives from school detectors

Journalists and fact-checkers verifying the authenticity of source materials and submitted content

Legal teams checking document authenticity in litigation and compliance workflows

Admissions officers screening college application essays for AI-generated content

About AI Text Detector

How AI Text Detection Works Without Machine Learning

Most AI content detectors like GPTZero, Originality.ai, Turnitin, and Copyleaks use proprietary ML models that require uploading your text to their servers. This detector takes a fundamentally different approach: pure statistical analysis that runs entirely in your browser. It exploits the measurable differences between how humans write and how large language models like ChatGPT, Claude, and Gemini generate text. Because LLMs predict the most likely next token, they produce text with statistically identifiable patterns in sentence length distribution, vocabulary diversity, phrase selection, structural repetition, and stylistic choices.

Why Burstiness Is the Strongest AI Detection Signal

Human writing naturally varies in sentence length — short punchy sentences mixed with longer explanatory ones. A human paragraph might contain a 4-word sentence followed by a 35-word sentence. AI models like ChatGPT (GPT-4, GPT-4o), Claude, and Gemini tend to produce more uniform sentence lengths, typically clustering between 15-25 words. This "burstiness" signal — measured as the coefficient of variation of sentence lengths — is one of the most reliable indicators of human vs AI writing because it reflects the natural rhythm and intentionality of human thought, which current LLMs struggle to replicate.

Signs of AI-Generated Text in 2026

Common markers of AI-generated content include: overuse of formal transition phrases like "Furthermore", "Moreover", "Additionally", and "It's worth noting"; low contraction rates ("do not" instead of "don't", "it is" instead of "it's"); excessive hedging language ("arguably", "it could be said", "generally speaking"); formulaic paragraph structures with consistent opening patterns; unusually uniform sentence lengths; repeated parallel phrasing; and minimal use of first-person pronouns, colloquialisms, and humor. Even the latest models — GPT-4o, Claude 3.5, and Gemini Ultra — exhibit these patterns when generating longer texts.

Which AI Writing Tools Can Be Detected

This detector identifies text from all major AI writing tools including OpenAI ChatGPT (GPT-3.5, GPT-4, GPT-4o), Anthropic Claude (3.5 Sonnet, 3.5 Haiku, Opus), Google Gemini (Pro, Ultra), Microsoft Copilot, Jasper AI, Writesonic, Copy.ai, Rytr, Sudowrite, Notion AI, Grammarly AI, and other tools built on these foundation models. All large language models share similar statistical text generation characteristics because they use the same fundamental approach: predicting the most likely next token. The multi-signal analysis detects these shared patterns regardless of which specific model generated the text.

Accuracy, Limitations, and Best Practices

Statistical analysis works best on text longer than 200 words. Very short texts (under 100 words), heavily human-edited AI text, text from non-native English speakers, highly technical or academic writing, and creative fiction may produce less accurate results. This tool provides a probability score, not a definitive judgment — no AI detector, including GPTZero and Turnitin, is 100% accurate. Always use AI detection results as one input alongside your own assessment and context. For best results, analyze a representative sample of at least 300 words from the document in question.

What Makes AI Writing Different from Human Writing?

AI language models like ChatGPT (GPT-4, GPT-4o), Claude, and Gemini generate text by predicting the most likely next token based on training data. This creates five measurable statistical differences from human writing. First, uniform sentence length — AI averages 15-25 words per sentence consistently, while humans naturally vary between 3 and 40+ words (high burstiness). Second, formulaic transitions — ChatGPT and Claude heavily overuse phrases like 'Moreover', 'Furthermore', 'Additionally', 'It's worth noting', and 'In conclusion'. Third, low vocabulary diversity — AI reuses common words instead of employing synonyms, idioms, or rare terms (hapax legomena). Fourth, formal register — AI avoids contractions ('do not' vs 'don't'), first-person pronouns, humor, and colloquialisms unless specifically prompted. Fifth, parallel structure — AI creates lists, paragraphs, and arguments with repetitive syntactic templates. These patterns are measurable with statistical analysis even without machine learning.

Why AI Content Detection Matters in 2026

With ChatGPT, Claude, Gemini, Copilot, Jasper, and hundreds of AI writing tools now ubiquitous, reliable AI content detection is critical across every industry. Academic integrity — universities and schools need to verify that student essays, dissertations, and homework represent genuine learning, not ChatGPT output. Google's helpful content system — Google explicitly prioritizes original, human-written content that demonstrates experience, expertise, authoritativeness, and trustworthiness (E-E-A-T). AI-generated SEO content risks ranking penalties. Publishing standards — editors and publishers need to verify content authenticity and maintain reader trust. Hiring and recruitment — recruiters need to evaluate genuine writing ability from cover letters, writing samples, and assessment submissions. Legal and compliance — AI-generated content in legal filings, contracts, and regulatory submissions raises authenticity concerns. Trust and transparency — readers, stakeholders, and audiences deserve to know whether content they consume was human-crafted or AI-generated. This free AI text detector helps address all of these use cases with 100% privacy.

AI Text Detector vs GPTZero vs Originality.ai vs Turnitin

The three most popular AI content detectors — GPTZero, Originality.ai, and Turnitin — all require uploading your text to their servers and use proprietary machine learning models. GPTZero offers a free tier but limits checks and stores submitted text. Originality.ai charges per scan and is aimed at content marketers. Turnitin is enterprise-only for educational institutions. This AI text detector takes a fundamentally different approach: pure statistical analysis running 100% in your browser. Your text never leaves your device. The trade-off is that ML-based detectors may be slightly more accurate on edge cases (paraphrased AI text, short samples), but this tool is completely free, unlimited, private, and transparent about exactly what each signal detected and why. For users who value privacy, cost, and transparency, this is the ideal choice.

Frequently Asked Questions

How accurate is this AI text detector?: This AI text detector uses 5 independent statistical signals to analyze writing patterns and achieves strong accuracy on texts over 200 words from ChatGPT, GPT-4, Claude, Gemini, and other major LLMs. Like all AI detection tools — including GPTZero, Originality.ai, and Turnitin — it provides probability scores rather than absolute answers. No AI detector is 100% accurate. Use the results alongside your own judgment and context for the most reliable assessment.
Can it detect ChatGPT, Claude, and Gemini content?: Yes. The detector identifies statistical patterns common to all major AI writing models including OpenAI ChatGPT (GPT-3.5, GPT-4, GPT-4o), Anthropic Claude (3.5 Sonnet, Opus), Google Gemini (Pro, Ultra), Microsoft Copilot, Jasper AI, Writesonic, Copy.ai, Notion AI, Grammarly AI, and others. All LLMs share similar text generation characteristics — uniform sentence lengths, formulaic transitions, low vocabulary diversity — that the multi-signal analysis detects.
Is my text sent to a server?: No. This AI content detector runs 100% in your browser using pure JavaScript with zero external dependencies. Your text never leaves your device — there is no server-side processing, no API calls, and no data storage. This makes it the most private AI text detector available, safe for analyzing student papers, confidential documents, legal text, and sensitive content.
What is burstiness in AI detection?: Burstiness measures how much sentence lengths vary in a text. Human writing naturally alternates between short punchy sentences (3-8 words) and longer explanatory ones (25-40+ words), creating high burstiness. AI models like ChatGPT and Claude produce sentences of more uniform length (15-25 words), resulting in low burstiness. Research shows burstiness is one of the most reliable statistical indicators for distinguishing human vs AI-generated text.
How do I check if text was written by ChatGPT?: Paste the text into this AI text detector and click Analyze. The tool checks 5 statistical writing signals: sentence burstiness (ChatGPT produces uniform sentence lengths), vocabulary richness (ChatGPT reuses common words), predictability (ChatGPT overuses phrases like 'Furthermore' and 'It's worth noting'), repetition patterns (parallel phrasing), and stylistic markers (low contraction rate, excessive hedging). You'll get an overall AI probability score and detailed signal breakdown explaining exactly what was detected.
What is the minimum text length for accurate results?: The tool requires at least 50 words to run analysis. For reliable results, we recommend at least 200-300 words. Longer texts provide more statistical data across all 5 signals and produce more accurate scores. For the best accuracy, analyze a representative sample of 300+ words from the content you're evaluating.
Can AI text that has been edited by a human fool the detector?: Heavily edited AI text may score lower on the AI probability scale, which is expected and correct behavior. If a human has significantly rewritten ChatGPT or Claude output — varying sentence lengths, adding personal voice and contractions, diversifying vocabulary, and breaking formulaic patterns — the text has genuinely become more human-like. Light edits (fixing typos, minor rewording) typically don't affect detection.
Does it work for non-English text?: The AI text detector is optimized for English text. The 50+ AI phrase patterns, stylistic analysis calibration, and contraction detection are specifically tuned for English writing. It may produce less accurate results for other languages. We plan to add support for additional languages in future updates.
What are the 5 AI detection signals?: The 5 signals are: (1) Sentence Burstiness (20% weight) — measures coefficient of variation in sentence lengths, consecutive differences, and monotone runs. (2) Vocabulary Richness (15% weight) — analyzes Type-Token Ratio, hapax legomena ratio, and repeated n-grams. (3) Predictability Analysis (25% weight) — scans for 50+ AI transition phrases, sentence-starter diversity, and formulaic paragraphs. (4) Repetition Patterns (15% weight) — detects structural repetition, parallel phrasing, and list-like patterns. (5) Stylistic Analysis (25% weight) — checks contraction rate, passive voice, hedging language, punctuation variety, and first-person usage.
How is this different from GPTZero, Originality.ai, and Turnitin?: GPTZero, Originality.ai, and Turnitin use proprietary ML models and require uploading your text to their servers. GPTZero has usage limits on free tier. Originality.ai charges per scan. Turnitin is enterprise-only for schools. This tool uses pure statistical analysis running 100% in your browser — your text is never uploaded. It's completely free, unlimited, and private. The trade-off is that ML-based tools may be slightly more accurate on edge cases, but this tool offers full transparency about exactly what each signal detected.
Can I use this for academic integrity checking?: Yes. Teachers, professors, and academic integrity officers can use this AI text detector to screen student essays, homework, dissertations, and exam responses for potential AI-generated content from ChatGPT, Claude, or Gemini. We recommend using the results as a starting point for conversation with students rather than as definitive proof, as no AI detector — including Turnitin's AI detection — is 100% accurate. False positives can occur with non-native English speakers and formulaic academic writing.
What does the Type-Token Ratio (TTR) measure?: Type-Token Ratio is the ratio of unique words to total words in a text. Human writing typically has higher TTR (0.6-0.8 for shorter texts) because humans naturally use diverse vocabulary, synonyms, and varied word choices. AI-generated text from ChatGPT and Claude tends to have lower TTR because language models reuse common, high-probability words. A low TTR combined with few hapax legomena (words used only once) is a strong indicator of AI authorship.
Is this AI text detector free?: Yes. This AI content detector is completely free with no usage limits, no signup required, no watermarks, and no ads gating results. You can analyze unlimited text. Since all processing happens locally in your browser with zero server costs, there is no need to charge. It will remain free.
Can it detect AI-generated code or technical writing?: The tool is optimized for natural language prose — essays, articles, blog posts, emails, cover letters, and academic papers. Code snippets, highly technical documentation, mathematical proofs, or text with many specialized terms may produce less reliable results due to inherently different statistical patterns. For best results on technical content, analyze the narrative/explanatory sections separately from code blocks.

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