Is Leap's AI detector free?

Yes. It's free with no signup, no word limit and no daily cap. It runs entirely in your browser, and your text is never sent anywhere.

Can it tell whether ChatGPT, Claude or Gemini wrote my text?

No. It reads writing habits that output from all of these models tends to share, so it can say a text reads like AI, but not which model wrote it.

How accurate is an AI detector?

No AI detector is fully accurate, and results vary with the text. Short inputs, formal writing, non-native English and heavily edited AI drafts are where mistakes are most common. OpenAI withdrew its own classifier in 2023 because of low accuracy. Treat any score, including Leap's, as one signal.

What AI detector do colleges use?

Many use Turnitin, which checks for AI inside the plagiarism checks they already run. GPTZero and Copyleaks are also used, sometimes inside Canvas, Blackboard or Brightspace. Check your syllabus or your school's academic integrity policy.

Can an AI detector be wrong?

Yes, in both directions. Detectors flag some human writing as AI and miss some AI writing. A score should never be the only basis for accusing anyone.

What should I do if my writing is flagged as AI?

Check which sentences triggered the flag and try a second detector. If you wrote it yourself, keep your drafts and version history and ask to talk it through. Rewriting your own work just to beat a detector rarely settles the question.

Does Leap keep or see my text?

No. The check runs in your browser tab. Your text isn't uploaded, stored or used to train anything.

AI Detector: Free AI Checker, No Word Limit

How to check text for AI

Paste at least 40 words. A full paragraph or more gives the signals more to read, and there is no word limit.
Press Check text. The score, the sentences that stand out and the five signals appear at once, because nothing has to travel to a server.
Open Every sentence to see each sentence's score in reading order. Rewrite the ones that read most machine-written, or run the draft through the AI humanizer and check it again.

No text handy? Try an example loads a paragraph written the way chatbots tend to write, so you can see what a high score looks like.

What your AI score means

0 to 29 (Reads human): few of the habits AI text tends to share. It doesn't prove a person wrote it.
30 to 59 (Mixed signals): some machine-like habits. Common in formal, technical or heavily edited writing.
60 to 84 (Likely AI): several habits at once, such as an even rhythm, stock phrases and hedging.
85 to 100 (Strongly AI): most signals are strong. Still a signal, not proof.

The score is a weighted mix of five signals, and each sentence gets its own score from the same signals. A high score on a few sentences in an otherwise human draft usually points to a pasted or AI-polished passage.

What the detector looks at

Even rhythm: how much sentence length varies. AI drafts tend to march along at one medium length, while people swing between short and long sentences.
Stock phrases: lines like "in today's fast-paced world", "delve into" and "it is important to note", counted per 100 words.
Hedging and transitions: words like "furthermore", "moreover" and "ultimately" that hold machine text together.
Em dashes: how often the text leans on em dashes or double hyphens.
Repeated words: how often the same longer words come back.

Leap doesn't run a language model, so it doesn't measure perplexity, the predictability of each word, which detectors like GPTZero use. That keeps it fast and private, and it means it reads style rather than authorship. For a high-stakes question, check with a second detector as well. Perplexity vs burstiness explains the difference.

How AI detectors work

AI-generated text tends to share statistical habits: a flatter vocabulary, sentences of similar length, and predictable word choices. Most detectors look for those habits with two measures. Perplexity is how surprising each next word is given the words before it. Burstiness is how much that surprise, and sentence length, varies across a text. AI output tends to score low on both. People make odd word choices and swing between terse and elaborate.Commercial detectors such as Turnitin, GPTZero and Copyleaks train classifiers on large sets of human and AI writing and report a probability. Mixed documents are common: a student who drafts with ChatGPT and then edits, or an editor who runs a human draft through AI for polish. A single document score smears those together, which is why sentence-level output helps. How AI detectors work goes into more detail.Short inputs are hard for every detector. Under about 50 words there isn't enough signal to separate styles, and false positives climb.

How accurate are AI detectors?

None is fully accurate, and the published numbers come with conditions. Turnitin says fewer than 1% of documents with 20% or more AI writing are wrongly flagged, and that about 4% of the sentences it highlights are human-written (Turnitin's accuracy, explained). OpenAI withdrew its own AI text classifier in July 2023 because of its low accuracy.Some writers get flagged more than others. A 2023 Stanford study found that seven detectors labeled, on average, 61% of TOEFL essays by non-native English speakers as AI-written (why non-native English gets flagged). Formal academic prose, lists and short answers also trip detectors. Leap's detector is simpler than the commercial ones, so treat its score as a first read. If your own writing was flagged, see AI detection false positives.

Which AI detectors do schools use?

Many colleges use Turnitin, which checks for AI inside the plagiarism checks they already run (does Turnitin detect AI?). Others use Copyleaks or GPTZero, and individual teachers often paste text into free detectors. Learning platforms don't detect AI themselves: Canvas, Blackboard and Brightspace show the score of whichever tool the school connects.

How Leap compares to other AI detectors

Leap: a quick private check of your own draft, with a score per sentence and the signals behind it. Free, no signup, no word limit.
Turnitin: integrity checks inside schools; teachers see the AI score, students usually don't. Licensed by schools.
GPTZero: teachers and students checking essays, with classroom tools. Free tier with a monthly word limit, paid plans.
Copyleaks: plagiarism and AI checks for schools and companies, often inside an LMS. Free scans with limits, paid plans.
QuillBot: a detector bundled with a paraphraser and grammar tools. Free with limits, paid plans.
ZeroGPT: a free paste-and-scan checker. Free with a per-scan limit, paid plans.

Head to head: Leap vs Turnitin, Leap vs GPTZero, Leap vs Copyleaks, Leap vs QuillBot and Leap vs ZeroGPT. For a wider list, see the best free AI detectors.

Who uses an AI content detector?

Teachers and professors use detectors to spot submissions that may have been drafted with AI. Most school policies require disclosure rather than banning AI outright, and a flag is a reason to talk, not an automatic fail. "These three paragraphs read as AI" is easier to discuss than a single percentage.Students check their own drafts before they submit, because formal academic writing shares a lot with AI writing and honest work sometimes gets flagged. Editors and publishers use detectors to triage freelance submissions, and content teams use them as a quick check before pages go live.

Flagged as AI? Clean it up

Leap's free AI humanizer is a cleanup pass that runs in your browser: it replaces stock AI phrases, removes em dashes and invisible characters, adds contractions, and marks same-length sentences so you can vary them. It doesn't guarantee passing any detector, but it makes writing read more naturally. If you wrote the text yourself and were flagged, how to contest a Turnitin false positive covers what to send your instructor.

Free AI Detector