What GPTZero does
GPTZero is an AI detector, launched in January 2023, that estimates whether a piece of text was written by a person or by models such as ChatGPT, Claude and Gemini. You paste text or upload a file and get a likelihood score with sentence-level highlights. Beyond detection it offers plagiarism checking, a grammar checker and Writing Replay, which plays back how a document was typed. It is used mainly by teachers and students, and also by publishers and recruiters.
Best for
- Teachers checking student essays for AI writing
- Students verifying their own work before submitting
- Editors and recruiters screening submitted text
- Schools that want detection inside Google Classroom or Canvas
Key features
Sentence-level AI detection
Scores text for likely AI authorship and highlights the passages that look machine-written.
Advanced Scan
A deeper analysis available on paid plans, with multilingual detection and downloadable reports.
Writing Replay
Shows a playback of how a document was written in Google Docs, including pastes and typing patterns.
Plagiarism and grammar
Checks for copied text without attribution and gives grammar and writing feedback.
Chrome extension
Runs detection inside Gmail, Google Docs, Google Classroom and social media pages.
Batch and LMS tools
The Professional plan scans up to 250 files at once, page by page, and connects to learning management systems.
GPTZero pricing
GPTZero has a free plan. You can scan up to 10,000 characters without paying; longer scans need a free account, and advanced features need a paid plan. Paid plans start at 18,99 €/month. Prices were shown in euros to a visitor in Europe; US prices may differ. Annual billing saves about 45% (Premium 9,99 €/month, Professional 19,99 €/month billed annually). The API is priced separately. A Professional Team plan (minimum 2 seats, shared credits, card payment only) is priced per seat at the Professional rate. Prices checked on the official site on Nov 9, 2026.
| Free | $0 | |
|---|---|---|
| Premium | 18,99 €/month | 300,000 words per month, Advanced Scan, multilingual detection, reports |
| Professional | 35,99 €/month | 500,000 words per month, up to 2 million words overage, 250-file batch scans, LMS integration |
Source: GPTZero pricing page
Pros and cons
What it does well
- Highlights which sentences look AI-written rather than giving only one overall score.
- Writing Replay gives evidence about how a document was produced, not just what it says.
- Works where teachers already are: Google Docs, Classroom, Canvas and a Chrome extension.
Know before you sign up
- Free scans are capped at 10,000 characters per scan without an account, and paid plans cap words per month.
- GPTZero itself says results should not be treated as a final verdict, since no detector is fully accurate.
- Team plans require at least 2 seats and card payment; invoicing needs a sales contact.
Alternatives to GPTZero
Originality.aiScreen text for possible AI generation.
GrammarlyCheck writing, tone, and clarity across your work.
Undetectable AIRewrite and review AI-assisted text.
DeepLTranslate text and documents across languages.
Hemingway EditorSpot readability issues and revise prose.
ProWritingAidPlan and edit stories with writer-focused feedback.
Questions about GPTZero
What is GPTZero?
GPTZero is an AI detector, launched in January 2023, that estimates whether a piece of text was written by a person or by models such as ChatGPT, Claude and Gemini. You paste text or upload a file and get a likelihood score with sentence-level highlights. Beyond detection it offers plagiarism checking, a grammar checker and Writing Replay, which plays back how a document was typed. It is used mainly by teachers and students, and also by publishers and recruiters.
Is GPTZero free?
GPTZero has a free plan. You can scan up to 10,000 characters without paying; longer scans need a free account, and advanced features need a paid plan. Paid plans start at 18,99 €/month. Prices were shown in euros to a visitor in Europe; US prices may differ. Annual billing saves about 45% (Premium 9,99 €/month, Professional 19,99 €/month billed annually). The API is priced separately. A Professional Team plan (minimum 2 seats, shared credits, card payment only) is priced per seat at the Professional rate. Prices checked on the official site on Nov 9, 2026.
How much does GPTZero cost?
Paid plans start at 18,99 €/month; plans listed on the official pricing page: Free ($0), Premium (18,99 €/month), Professional (35,99 €/month). Prices were shown in euros to a visitor in Europe; US prices may differ. Annual billing saves about 45% (Premium 9,99 €/month, Professional 19,99 €/month billed annually). The API is priced separately. A Professional Team plan (minimum 2 seats, shared credits, card payment only) is priced per seat at the Professional rate.
Who is GPTZero best for?
Teachers checking student essays for AI writing, Students verifying their own work before submitting, Editors and recruiters screening submitted text and Schools that want detection inside Google Classroom or Canvas.
Where can I use GPTZero?
GPTZero is available on Web, Chrome extension and API, according to its official site.
What are some alternatives to GPTZero?
Similar writing tools include Originality.ai, Grammarly, Undetectable AI and DeepL. Compare them on the Writing page.