GPTZero is a freemium AI detector that checks whether text was written by a human or by AI models such as ChatGPT, Claude and Gemini. It is popular with teachers, students and editors. The free plan scans up to 10,000 words a month, and paid plans start at $12.99 a month billed yearly.
What is GPTZero?
GPTZero is an AI content detector built to tell human writing apart from text generated by large language models. You paste text or upload a file, and it highlights sentences that look AI-written and gives an overall probability that the document was produced by AI.
It started as a student project in early 2023 and has grown into a full writing-integrity platform. Today it also offers plagiarism checking, writing replay that shows how a document was typed, a hallucination detector, and integrations with Google Docs, Canvas and other learning tools.
GPTZero key features
AI detection
Scores text as human, AI or mixed, with an overall probability.
Sentence highlighting
Highlights the exact sentences most likely written by AI.
Plagiarism check
Compares text against web sources to flag copied passages.
Writing replay
Shows how a Google Doc was written over time to prove authorship.
Hallucination detector
Flags citations and claims that may be invented by AI.
Batch file scanning
Upload many files at once on higher plans.
Chrome extension
Check AI content in Gmail, Google Docs, Classroom and social media.
Downloadable reports
Export detailed AI reports to share with students or clients.
API and LMS integrations
Add detection to your own app or to Canvas, Moodle and other LMS tools.
GPTZero pricing plans (2026)
You can start for free with a monthly word limit. Paid plans raise the word allowance, unlock advanced scans and add features for schools and teams. Annual billing saves around 45%.
Free
10,000 words a month with basic AI scans and limited advanced scans.
Premium
300,000 words a month, advanced scans, multilingual detection and reports. $12.99/mo billed yearly.
Professional
500,000 words, batch file scans, LMS integrations and stronger security. $24.99/mo billed yearly.
Team and Enterprise
Shared credits, central billing, admin controls and API access for schools and companies.
Prices checked in October 2026 (USD). Local prices may differ, so confirm on the official pricing page before you buy.
How to use GPTZero
- 1
Go to gptzero.me and create a free account.
- 2
Paste your text or upload a document into the AI Detector box.
- 3
Click Scan and review the overall AI probability score.
- 4
Check the highlighted sentences to see which parts look AI-written.
- 5
Download the report or use writing replay if you need proof of authorship.
Who should use GPTZero?
Teachers
Check essays and assignments for AI-written content before grading.
Students
Make sure your own work will not be wrongly flagged before you submit it.
Editors and publishers
Screen freelance articles and guest posts for AI-generated text.
Recruiters
Review cover letters and writing tests for AI use.
Pros and cons
What we like
- Generous free plan to try it
- Sentence-level highlighting is easy to read
- Extra tools for plagiarism and authorship
- Integrations with Google Docs and LMS platforms
Watch out for
- No AI detector is 100% accurate
- Short texts are harder to judge reliably
- Heavily edited AI text can slip through
- Best features need a paid plan
Best GPTZero alternatives
GPTZero is one of the most trusted AI detectors, especially in education. The free plan is enough for occasional checks, while Premium suits teachers and editors who scan content every week. Use its results as a guide alongside your own judgement, not as final proof.
GPTZero FAQs
Is GPTZero free?
Yes. The free plan lets you scan up to 10,000 words a month with basic AI detection and a few advanced scans.
How much does GPTZero cost?
Premium costs $23.99 per month, or $12.99 per month billed yearly. Professional costs $45.99 per month, or $24.99 per month billed yearly.
How accurate is GPTZero?
GPTZero is among the more accurate AI detectors, but no tool is perfect. Short or heavily edited texts can give uncertain results, so treat scores as a signal, not proof.
Can GPTZero detect ChatGPT and Claude?
Yes. It is trained to detect text from popular models, including ChatGPT, Claude and Gemini.
Who created GPTZero?
GPTZero was created by Edward Tian and Alex Cui and launched publicly in January 2023.
Does GPTZero work in Google Docs?
Yes. The Chrome extension and writing replay features work with Google Docs, Gmail and Google Classroom.
