GPTZero
GPTZero · Detecção de IA
GPTZero is an AI detector that tells you whether a piece of writing came from a large language model such as ChatGPT, Gemini, or Claude. It scans at the document, paragraph, and sentence level, highlights the exact passages it flags, and explains in plain language why it scored them as machine-written. Think of it as an AI content detector with an opinion you can read. Teachers, publishers, recruiters, and writers use it to check academic work, submissions, and drafts before those texts go any further.
Sobre GPTZero
What Is GPTZero
GPTZero is a web-based AI detection tool built to answer one question: did a person write this, or did a model generate it? Founded in January 2023 out of Princeton's NLP lab, it works on prose, the kind of writing you find in essays, articles, reports, and job applications. The company says it has served over 10 million users and works with more than 100 organizations across education, hiring, and publishing. It's also one of the few AI writing checkers that marks individual sentences rather than the whole page.
The detection model looks for signals that separate human writing from generated text. The main ones it points to are perplexity, which asks how predictable the word choices are, and burstiness, which measures how much sentence length and rhythm vary. AI text tends to be smooth and even. Human writing jumps around. GPTZero weighs hundreds of these factors to detect AI-generated text, then returns a score along with sentence-level highlights.
GPTZero isn't a verdict machine, and the company says so directly. No detector is fully accurate. Scores are a signal, not a sentence. Results get better with longer text, and the strongest performance is on English prose. GPTZero recommends treating a flag as a starting point for a conversation, not as proof that someone cheated.
Getting Started
- Open the GPTZero site and paste your text or upload a document, then hit Scan. Scans longer than 10,000 characters need a free account first.
- Read the results. GPTZero shows the share of the text it thinks is AI-written and highlights the specific sentences behind that score.
- Create a free account if you want more room. Signed-in users can scan texts up to 150,000 characters or run a batch of up to 250 files.
- Add the Chrome extension if you'd rather check pages as you browse, or install the Google Docs and Microsoft Word add-ins to scan inside the tools you already write in.
- Upgrade to a paid tier when you hit the free limits, and use the API if you need detection wired into your own platform.
Informações do produto
Uma visão rápida dos preços, das plataformas compatíveis e do desempenho de GPTZero.
Ideal para
Os usuários, tarefas e cenários em que esta ferramenta se encaixa melhor.
Usuários
- Teachers and professors
- Students and ESL writers
- Editors, publishers, and recruiters
Tarefas
- Checking a submitted essay or assignment
- Reviewing a freelance article or manuscript before publication
- Verifying cited sources and bibliographies
Cenários
- A teacher who suspects a paper was generated overnight
- A newsroom screening a stack of reader submissions
- A developer adding AI checks to a writing platform
Principais recursos
Sentence-Level AI Detection With Reasons
Most detectors hand you a single number and leave it there. GPTZero points to the exact sentences it thinks a model wrote and explains the reasoning in plain language, so you can judge the call yourself. That clarity is the point. The trade-off is that accuracy drops as the unit gets smaller: document-level results are more reliable than paragraph-level, which beats sentence-level. Shorter text, weaker signal.
Mixed-Document Detection
Real documents are often part human and part machine, especially when someone drafts with AI and then edits by hand. GPTZero says it handles these mixed texts at 96.5% accuracy, higher than many tools that break down when human and AI writing sit in the same paragraph. That matters if you're checking work that was partly assisted rather than fully generated. A single flagged sentence shouldn't sink an otherwise human essay.
Writing Replay and Authorship Analysis
The Origin Chrome extension and Writing Report let you see how a document came together. It replays editing activity in Google Docs and surfaces typing-pattern signals and collaborator evidence. Think of it as a flight recorder for writing. A student can use the same trail to show their work was their own, which turns the feature into a defense as well as a check.
Plagiarism and Citation Checks
Beyond AI detection, GPTZero checks text against online sources for unattributed content and verifies citations against a bibliography. It supports MLA, APA, Chicago, IEEE, and BibTeX. The source checker is aimed at the specific problem of AI-written text inventing references that look real but don't exist. Fake citations are easy to miss by eye.
Broad Model Coverage and Multilingual Support
The detector works across ChatGPT, GPT-5, GPT-4, and GPT-3, plus Gemini, Claude, Llama, and Deepseek, so a ChatGPT detector and a Gemini detector are the same tool here. The company has retrained on newer models including GPT-4.1 and Gemini 2.5. It fully supports English, German, Portuguese, French, and Spanish, and says it's used in over 100 countries. Accuracy is strongest on English prose.
Developer API
The API lets you run detection inside your own product instead of sending users to a separate site. GPTZero ships ready-to-use sample code in 17 languages, including Node.js, Python, C#, Java, and PHP, so integration doesn't start from a blank page. For anything past casual use, the AI detector API is the piece that matters.
Prós e contras
Prós
- Sentence-level highlighting with written explanations shows why text was flagged, which is more useful than a bare score.
- Handles mixed human-and-AI documents, a gap where simpler detectors tend to fail.
- Free tier with a Chrome extension and Google Docs and Word add-ins means you can test it inside your normal workflow.
- Debiased training lowers false positives on ESL writing, a known weakness across this category.
- API with sample code in 17 languages supports building detection into existing platforms.
Contras
- Accuracy falls at the sentence level, so short passages can be flagged or missed more easily than full documents; short text is the least dependable use case.
- The classifier can mistake other machine-generated or highly procedural text for AI, which limits how well it works on technical or formulaic writing.
- Heavily edited AI output is harder to catch, so a determined rewriter can slip past detection.
- Free scanning is capped at 10,000 words a month, so anyone checking regularly will need a paid plan.
Perguntas frequentes
It checks whether text was written by a person or generated by a model like ChatGPT or Gemini, and points to the specific sentences behind that call. Schools, publishers, and recruiters use it to screen writing before deciding what to do next.
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