GPTZero
AI detector that estimates how much of a text was written by ChatGPT, Claude or Gemini.
Updated · AppBreakup editorial · Web, Browser extension
Is GPTZero free?
Free plan, plus paid plans
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All 6
Originality.aiCompareStarting price: $12.95/month billed annually (Pro); $14.95 monthly
GrammarlyStarting price: $12 per member/month billed annually ($30 monthly), Pro
ZeroGPTCompareFree plan: $0 forever
- Verified facts
- 5 of 5
- Alternatives ranked
- 6
- Approved reviews
- 0
- Visits sent from here
- 0
About GPTZero
GPTZero checks a piece of writing and estimates how likely it is to be AI-generated, highlighting the sentences that look machine-written. It started in early 2023 as a tool for teachers worried about ChatGPT essays and is still aimed mostly at education, with integrations for Google Docs, Google Classroom and Canvas plus a Chrome extension. Around the core detector it has added a plagiarism checker, a grammar and feedback tool, and Writing Replay, which shows how a Google Doc was typed over time as evidence of authorship. You can paste short texts without an account; longer scans and the extra tools need a free account or a paid plan, and teams can buy shared word allowances. A developer API lets schools and platforms build detection into their own products. Like every AI detector, its scores are probabilities rather than proof, so results are best used as a prompt for a conversation rather than as a verdict.
Best for: Teachers and schools that want an AI check built into Google Docs, Classroom and Canvas.
Pros and cons
What works
- Short texts can be checked without signing up
- Writing Replay shows how a document was actually typed
- Integrations with Google Docs, Classroom, Canvas and Zapier
- Full support for five major European languages
Why people leave
- Detection scores are estimates and can mislabel human writing
- Longer scans and extra tools sit behind an account or paid plan
- Plan prices on the pricing page only load with JavaScript
GPTZero vs Originality.ai, Grammarly and ZeroGPT
From each app's listing and the prices verified on its own site. A dash means we haven't verified it yet.
| Attribute | GPTZero | Originality.ai | Grammarly | ZeroGPT |
|---|---|---|---|---|
| Pricing | Free plan + paid | Free plan + paid | Free plan + paid | Free plan + paid |
| Verified price | — | $12.95/month billed annually (Pro); $14.95 monthly | $12 per member/month billed annually ($30 monthly), Pro | — |
| Free plan | Yes | Yes, 10K words one time | Yes, $0 a month with 100 AI prompts | $0 forever |
| Open source | No | No | No | No |
| Self-hostable | No | No | No | No |
| Platforms | Web, Browser extension | Web, Browser extension | Web, Windows, macOS, iOS, Android, Browser extension | Web |
Full GPTZero vs Originality.ai comparisonFull GPTZero vs ZeroGPT comparison
Top GPTZero alternatives
See all 6- 1Originality.ai68.8
Built for publishers and SEO teams, with plagiarism, readability and fact-checking in one credit-based plan.
- 2Grammarly66.2
Includes a free AI detector next to its grammar checker, plus authorship tracking that helps writers show their work is their own.
- 3ZeroGPT57.5
Free AI text detector you can use without an account for quick checks of essays and articles.
- 4
QuillBot54.8Offers a free AI detector inside a broader paraphrasing and grammar toolkit, handy for quick checks.
- 5
Pangram42.3Research-backed detector with a very low false-positive rate and segment-level AI highlighting.
Why people left GPTZero
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GPTZero: common questions
What is GPTZero?
GPTZero: AI detector that estimates how much of a text was written by ChatGPT, Claude or Gemini. Best for teachers and schools that want an AI check built into Google Docs, Classroom and Canvas. Available for Web and Browser extension.
Is GPTZero free?
GPTZero has a free plan and paid plans.
Is GPTZero open source?
No, GPTZero is not open source.
What platforms does GPTZero run on?
GPTZero is available for Web and Browser extension.
What are the best alternatives to GPTZero?
The highest-ranked GPTZero alternatives right now are Originality.ai, Grammarly and ZeroGPT. See the full ranked list for pricing, platforms and verified facts.
GPTZero vs Originality.ai: what's the difference?
Both GPTZero and Originality.ai are free with paid plans. Both run on Web and Browser extension.