GPTZero

GPTZero is an AI-text detector built for teachers and schools. Princeton student Edward Tian created it to protect academic honesty in the age of AI writing tools. It studies how writing is built — how predictable the word choices are and how sentence length varies — to judge whether a person or a machine wrote the text. Teachers, editors, and publishers use it to check student work and submissions for AI-generated content. It offers a free tier and paid plans for heavier use.

Key Features

Sentence-Level Highlighting

Marks the exact sentences likely written by AI and shows a confidence score for each one, so you see the evidence behind the verdict.

Perplexity and Burstiness Analysis

Measures how predictable the wording is and how sentence length shifts across a document — the two signals that reveal machine writing.

Writing Replay

Replays the writing history of a Google Doc, showing whether a draft was typed over several days or pasted in all at once.

Batch Scanning

Uploads and checks many documents in one go, which saves time when a whole class set of papers needs review.

Plagiarism Checks

Paid plans combine AI detection with plagiarism scanning in a single pass, so one check covers both kinds of copying.

LMS and API Integrations

Connects with Canvas, Google Classroom, and Moodle on institutional plans, and developers can add detection to their own apps with the API.

FAQ

How accurate is GPTZero?

Strong on raw AI output, imperfect on edited text. Independent tests give it high marks for unedited AI writing, but heavily edited or paraphrased text can slip past. Use it as one signal among several, not a final verdict.

What does the free plan include?

The free tier covers 10,000 words per month with no credit card required. It includes basic AI scans and limited advanced scans — enough for a teacher checking work now and then.

Which AI models can it detect?

ChatGPT, GPT-4, Claude, Gemini, Llama, and other major models. The detection model is updated regularly as new AI models appear.

How does it fit into classroom workflows?

Through Canvas, Google Classroom, and Moodle integrations on institutional plans. Individual teachers can also scan text in a browser or use the Chrome extension inside Google Docs.

Can AI-generated text bypass it?

Yes — heavily edited or paraphrased AI text may evade detection. That is true of every AI detector. Review flagged work with human judgment before making accusations.

Conclusion

GPTZero is the educator's AI detector: sentence-level evidence, writing replay, and a generous free tier built for classroom reality. Paid plans scale it up for schools, teams, and publishers. No detector is perfect, so use its results as evidence rather than final proof — but for originality checks, GPTZero earns its place and stays honest about its limits.