About Detect AI

Our mission

The volume of machine-written text has exploded, and most people have no easy way to tell where words come from. Our mission is to give everyone a fast, transparent, and genuinely free AI detector, so that judgments about authorship rest on evidence rather than guesswork. We believe that as AI writing becomes normal, the ability to detect AI writing should be a public utility, not a luxury locked behind subscriptions.

We focus on clarity over hype. Rather than promising impossible certainty, our AI content detector explains what it measures and how confident it is, so you can weigh the result with judgment. Every score is a starting point for a human decision, and that principle guides how we design and describe the tool.

How our AI detector works

Our AI checker analyzes the linguistic fingerprints that separate machine text from human text, and the most important signal is perplexity. Perplexity measures how predictable a passage is to a language model: when each word is the statistically obvious next choice, perplexity is low. AI models are trained to produce smooth, high-probability wording, so their output tends to be strikingly low in perplexity compared with the messier, less predictable phrasing people naturally use.

The second signal is burstiness, the variation in sentence length and rhythm across a passage. Humans write in bursts, mixing short punchy sentences with long winding ones, while AI text often stays uniform and evenly paced. Our ChatGPT detector combines perplexity and burstiness into a single probability score, weighing both patterns so that neither signal alone drives the outcome and the result reflects the overall texture of the writing.

Which AI models we detect

Detect AI is tuned to recognize output from today's most widely used systems, including OpenAI's ChatGPT, GPT-4o, and GPT-4, Google Gemini, and Anthropic Claude. It also covers open and independent models such as Meta's Llama, DeepSeek, and Mistral. Because these systems share the same core tendency toward low-perplexity, low-burstiness text, our AI text detection generalizes well even to newer releases, though very short samples always carry more uncertainty than longer ones.

Accuracy and honest limits

No AI content detector is perfect, and we would rather be honest than oversell. Accuracy improves with longer passages, because a few hundred words give the model far more statistical evidence than a single sentence. Heavily edited AI text, machine translation, and the writing of non-native speakers can all blur the signals, which is why we report a probability rather than a simple yes or no.

Please treat every result as probabilistic evidence, not proof. A score is an informed estimate, and it should never be the sole basis for an accusation, a failing grade, or any form of punishment. Use Detect AI as one input alongside your own knowledge of the writer, the context, and a direct conversation, and give people the benefit of the doubt when a score is uncertain.

Why it's free

Detect AI is supported by advertising, and that is exactly why it can stay free for everyone. Ads let us cover the cost of running the servers without charging users, gating features, or capping how many checks you can run. We think an AI detector this useful should be reachable by a student on any budget or a small newsroom without a software line item, so keeping it open and free is a deliberate choice, not a trial.

The team behind Detect AI

Detect AI is built by a small team that has worked on AI detection since large language models first went mainstream. Our roots are in the Korean market, where we run GPTKiller, a Korean-language AI detector trusted by educators and writers there. Detect AI is the English-language counterpart of that project, bringing the same detection approach to a global audience while GPTKiller continues to serve Korean readers.

Privacy and our values

We are privacy-first by design. Text you paste is analyzed in real time and is not stored on our servers after your result is returned, so your drafts, essays, and documents stay yours. We do not build profiles from your submissions or sell your content, and you can read the full details in our privacy policy. Transparency, fairness, and respect for the people behind the words guide everything we do.