2026 Review

GPTZero

AI-writing detector used by schools and editors, with sentence-level highlighting and reports.

Writing EducationFreemiumAPIPopular71% positive

Facts checked Aug 9, 2026

About GPTZero

GPTZero is the best-known AI text detector: paste or upload writing and it scores how likely it is to be machine-generated, highlighting the specific sentences it flags rather than returning one number. It also detects paraphrasers and mixed human/AI text, checks for plagiarism and hallucinated citations, and produces downloadable reports for academic-integrity cases. The free plan covers 10,000 words a month with no card; Premium is $23.99/month or $12.99/month billed annually for 300,000 words.

At a glance

Founded: 2023
Headquarters: New York, US
Users: over 10 million teachers and students (company claim)
Platforms: Web, Browser extension

Integrates with

Google DocsGoogle ClassroomCanvasMicrosoft WordGoogle Chrome

Main competitors

TurnitinOriginality.aiCopyleaksZeroGPT

Best for

Academic integrityEditorial checksHiring screensContent audits

Pros

The sentence-level view makes the result arguable rather than a black-box accusation
Writing Replay shifts the evidence from prediction to process, which is far more defensible
Free tier of 10,000 words a month is enough for individual teachers and editors
Widest model coverage and the most established name — an AFT partner used across 100+ countries

Cons

No AI detector is reliable enough for a disciplinary decision on its own — false positives fall hardest on non-native English writers
Independent testing puts real-world accuracy well below the marketing figures, with a meaningful false-positive rate
Paying monthly costs $23.99 against $12.99 billed annually — a 45% penalty for flexibility
The detection arms race means results drift as models change, so old scans age badly

Our verdict

Best for: Teachers, editors and recruiters who need a documented first-pass signal, used alongside human judgement.

Skip if: You want a verdict you can act on unilaterally — no detector is accurate enough to carry that weight.

Our review

GPTZero is the detector everyone has heard of, and it earns the position with the surrounding workflow more than with the model. The sentence-level highlighting matters: a document-level percentage is an accusation nobody can discuss, whereas 'these four sentences' is the start of a conversation with a student. Add paraphraser detection, plagiarism checking, hallucinated-citation flagging and LMS integration for Canvas and Google Classroom, and it covers the whole academic-integrity job rather than one slice of it.

The honest problem is the one the entire category has. GPTZero cites 99% accuracy on the RAID benchmark; independent testing has landed closer to 85% detection with roughly a 9% false-positive rate, and research on AI detectors has repeatedly shown they misclassify non-native English writing at far higher rates — Stanford researchers found detectors flagging a majority of TOEFL essays as machine-written. Those errors are not evenly distributed, and they land on exactly the students least able to contest them. Any institution using this to make disciplinary decisions on the score alone is misusing it, and the vendor's own guidance says as much.

That is why Writing Replay is the most interesting thing GPTZero ships. Instead of predicting whether text looks generated, it records how a document was actually composed — pauses, revisions, pasted blocks. Process evidence is dramatically harder to fake and dramatically easier to defend in a hearing, and it points to where this category should end up. On price, the free 10,000 words a month is genuinely enough for an individual teacher, and the 45% annual discount is worth taking if you are buying at all.

Verdict: the most complete AI-detection toolkit and a reasonable first-pass signal for teachers, editors and recruiters — as long as it is used as a prompt to look closer rather than a verdict to act on. If you need certainty, no product in this category can sell it to you.

What reviewers elsewhere say

71% positive — Teachers value the highlighting and reports as a starting point for a conversation; the loudest criticism is false positives on non-native and neurodivergent writers, and students disputing scores they cannot contest.

Sentiment estimated from reviews on Reddit, Trustpilot, Product Hunt, as of Aug 2026. Third-party scores are point-in-time snapshots. We don't host user reviews.

Key features

Multi-model detection tuned for ChatGPT, Claude, Gemini and Llama output
Sentence-level highlighting plus mixed human/AI detection rather than a single document verdict
Paraphraser and AI-bypasser detection for text run through humanising tools
Writing Replay and authorship tracking, which show how a document was actually composed
Plagiarism checker, hallucination detector and downloadable reports for integrity cases
Batch scanning (50 files on Premium, 250 on Professional) and LMS integrations for Canvas and Google Classroom

How to use GPTZero

Paste text or upload a document — the free plan covers 10,000 words a month with no card.
Read the sentence-level highlighting, not just the headline percentage.
Use Writing Replay where it is available: composition history is far stronger evidence than a prediction.
Treat a high score as a prompt for a conversation, never as a finding — false positives cluster on non-native writers.
For classes, connect Canvas or Google Classroom on Professional and scan batches rather than files one by one.
Re-scan rather than relying on old reports — detection accuracy shifts as models change.

Pricing

Deal: Annual billing saves 45% on Premium and Professional

Free$0

10,000 words per month, basic AI detection, no card required.

Premium$23.99/mo

$12.99/mo billed annually. 300,000 words/month, 50,000 characters per scan, advanced scan, multilingual detection, batch of 50, downloadable reports.

Professional$45.99/mo

$24.99/mo billed annually. 500,000 words/month, 150,000 characters per scan, batch of 250, page-by-page scanning, LMS integration.

Teams & EnterpriseCustom

Shared credits, unified billing, roles and provisioning. Separate API pricing for developers.

Pricing verified August 2026 · prices as listed by the vendor; check the official site for current offers.

Try GPTZero

Frequently asked questions

What is GPTZero?

GPTZero is an AI-writing detector launched in 2023 by Edward Tian and co-founders. It scores how likely text is to be machine-generated, highlights the specific sentences it flags, detects paraphrased and mixed human/AI writing, and adds plagiarism and hallucinated-citation checks. The company says over 10 million teachers and students use it across more than 100 countries.

How much does GPTZero cost?

The free plan covers 10,000 words a month with no credit card. Premium is $23.99/month or $12.99/month billed annually for 300,000 words, and Professional is $45.99/month or $24.99/month billed annually for 500,000 words with batch scanning and LMS integration. Teams, Enterprise and API pricing are quoted separately.

How accurate is GPTZero?

GPTZero cites 99% accuracy on the independent RAID benchmark, but independent real-world testing has put it closer to 85% detection with a false-positive rate near 9%, and academic work has shown AI detectors in general misclassify non-native English writing at much higher rates. It is a useful signal and a poor verdict — treat a flag as a reason to look closer, not as proof.

Does GPTZero have an API?

Yes. There is a developer API with ready-made examples in 17 languages, priced separately from the consumer plans, used to wire detection into LMS platforms, publishing pipelines and hiring tools.

Can students get around GPTZero?

Sometimes, and the tool knows it — which is why it also detects paraphraser and 'humaniser' output. The more durable answer is process rather than prediction: Writing Replay and authorship tracking record how a document was composed, which is far harder to fake than a text pattern and far more defensible in an integrity hearing.