Check whether text was written by AI. Paste your content and get an instant AI probability estimate based on burstiness, sentence variance, vocabulary predictability, repetition, and punctuation patterns — all analyzed in your browser. Nothing is uploaded.
Check if text was written by AI for free at practicalwebtools.com/ai-tools/ai-content-detector. Paste or type your text and the tool analyzes five statistical signals — sentence-length variance, burstiness, a perplexity proxy, repetition patterns, and punctuation habits — to estimate the probability the text was AI-generated. Analysis runs entirely in your browser: no text is uploaded, stored, or sent to a server. The result is an estimate based on measurable patterns, not a definitive verdict, so treat borderline scores with judgment.
Paste the text you want to check into the editor (or type directly). Aim for at least 50 words for a meaningful signal.
Click Detect AI Content. The analysis runs instantly in your browser — no network request is made.
Review the overall AI Probability gauge and read the per-signal breakdown to understand which patterns drove the score.
Scroll to the sentence highlighter to see the specific sentences flagged as most AI-like, then use your judgment alongside the score.
It analyzes five statistical signals that tend to differ between human and AI writing. Sentence-length variance measures how much sentence length varies — humans write in bursts of short and long sentences, while AI is more uniform. Burstiness captures that clumping of varied sentence lengths. A perplexity proxy estimates how predictable the word choices are using vocabulary diversity and the ratio of common words. Repetition analysis detects repeated transitional phrases and sentence openers. Punctuation analysis flags predictable use of em-dashes and colons. The five signals are weighted and combined into an overall AI Probability score.
No heuristic detector is perfect, and this tool is transparent about that. It estimates the probability that text was AI-generated based on measurable statistical patterns — it is not a definitive verdict. Very high scores (80%+) and very low scores (under 20%) are usually reliable indicators. Scores in the middle (30–70%) are genuinely ambiguous and should be treated with human judgment. AI detectors in general, including commercial ones, produce false positives on human writing and false negatives on heavily edited AI text. Use this as one signal, not as proof.
No. All analysis runs entirely in your browser using JavaScript. Your text is never sent to any server, stored, or logged. This makes the tool safe for confidential documents, unpublished drafts, and sensitive content. Because nothing is uploaded, there are also no rate limits, no signups, and no costs.
The tool estimates whether text was AI-generated in general; it does not identify which specific model produced it. ChatGPT (GPT-3.5, GPT-4, GPT-4o), Claude, Gemini, and other large language models share many of the same statistical fingerprints — low burstiness, uniform sentence length, predictable vocabulary, formulaic transitions — so they all tend to score as AI-generated. Distinguishing between specific models is not reliable with heuristic analysis.
Yes, completely free with no signup, no API key, and no usage limits. Because the analysis runs entirely in your browser, there are no server costs to pass on. You can run as many checks as you like.
At least 50 words gives a meaningful signal; 200+ words improves reliability. Very short snippets (under 50 words) do not provide enough statistical variation to distinguish reliably between human and AI writing, so the score should be treated skeptically. For best results, paste a full paragraph or more.
Yes. Heavily edited AI text — where a human rewrites sentences, varies length, and removes formulaic transitions — can score as human on any detector, including this one. Conversely, careful human writing that happens to be uniform and formal can occasionally score as AI. This is why no detector should be treated as definitive. The tool reports the statistical likelihood, not certainty.
Burstiness measures variation in sentence length and complexity across a passage. Human writing is bursty: a short punchy sentence, then a longer complex one, then medium ones, creating an irregular rhythm. AI tends to produce smoother, more uniform prose with less length variation. Low burstiness is one of the strongest statistical indicators of AI-generated text.
Perplexity measures how predictable the next word is given the previous words. AI models are trained to pick high-probability words, so AI text tends to have low perplexity (highly predictable word choices). Humans use more surprising, varied vocabulary. This tool uses a perplexity proxy — vocabulary diversity and the ratio of common words — because computing true perplexity requires a language model, which would mean sending text to a server. The proxy correlates well with the real metric.
GPTZero and Originality.ai run their analysis on servers using trained machine-learning models, which can be more accurate but require uploading your text. This tool runs entirely in your browser using transparent heuristics — your text never leaves your device. It is the better choice when privacy matters (confidential documents, unpublished work) or when you want to understand why text scores a certain way, since it shows the per-signal breakdown.