Free AI detector to detect AI content

To detect AI content means analyzing a piece of writing and estimating how likely it was produced by an AI language model rather than a person. As tools like ChatGPT, GPT-4 and Claude make it effortless to generate essays, articles and emails, telling human writing apart from AI writing has become genuinely hard. Detect AI is a free AI detector built to close that gap in seconds.

Unlike a plagiarism scanner, an AI detector doesn't compare your text against a database of sources. Instead, it studies the statistical fingerprints of the writing itself — how predictable each word is, how sentences are structured, and how much natural variation the text contains. Human writing tends to be less predictable and more varied; AI-generated text is usually smoother and more uniform. Our model reads those patterns and turns them into a single, clear AI probability score.

Whether you need to detect ChatGPT in student submissions, keep your blog authentic and Google-friendly, or simply check whether a message was written by a bot, Detect AI gives you a clear percentage and highlights the exact sentences that look AI-generated.

Detect AI is a free AI content detector that tells you whether a piece of writing was more likely produced by a human or by a large language model. Paste any paragraph, essay, article, or email and our AI checker returns an instant probability score — no account, no credit card, and no per-day cap. Because everything runs through a lightweight web app, you can detect AI writing from your laptop or phone in seconds.

Under the hood, our ChatGPT detector studies the same statistical fingerprints that separate machine text from human text: perplexity (how predictable each word is) and burstiness (how much sentence length and rhythm vary). Text from ChatGPT, GPT-4o, Gemini, and Claude tends to be smooth and low-perplexity, while genuine human writing is burstier and less predictable. Combining these signals lets the detector flag AI-generated content with useful confidence.

Teachers use it to screen essays, editors and SEO teams use it to keep content authentic, and writers use it to double-check their own drafts before publishing. It is popular with students who want to confirm that paraphrased notes still read as their own work, and with recruiters reviewing cover letters. Whatever the use case, the AI detector stays free and unlimited — that is the whole point.

Prefer to work in Korean? Our sister project GPTKiller brings the same AI text detection to Korean-language writing. To learn more about how the technology works, our accuracy philosophy, and why we keep the tool free, read the about page. AI detection is probabilistic, so always treat the score as a strong signal rather than absolute proof.