GPTZero Alternatives: 7 AI Detectors Compared

The best GPTZero alternatives in 2026 are Pangram if accuracy matters most, Originality.ai for publishers who also need plagiarism and fact checks, Copyleaks for organisations that work in many languages, Grammarly if you already write in it, QuillBot and Scribbr for free checks of up to 1,200 words, and RealWrite if you want to see why each sentence was flagged and fix it in the same place. ZeroGPT is free and quick but is a different tool from GPTZero, with a record of flagging human writing.

A disclosure before we start: RealWrite makes an AI detector too. We include it, say where it falls short, and keep to facts anyone can check. Prices are the US prices on each vendor's own pricing page, help centre or App Store listing, checked on 21 October 2026. Several of these tools price by region, so you may see different numbers.

GPTZero and ZeroGPT are different tools

The names cause a lot of confusion, so first:

• GPTZero (gptzero.me) was built by Edward Tian and Alex Cui. In June 2026 Superhuman, the company formerly called Grammarly, agreed to acquire it and said it will keep running as a standalone product.
• ZeroGPT (zerogpt.com) is run by Olive Works LLC, a Wyoming company. It has nothing to do with GPTZero.

If you were looking for one of them and found the other, that is why.

What GPTZero does well

GPTZero is a strong, education-focused detector:

• A free plan with 10,000 words a month and up to 10,000 characters per scan
• Sentence-level highlighting on every plan
• A Chrome extension, Google Docs and LMS integrations (Canvas, Google Classroom) and an API
• Full support for English, German, Portuguese, French and Spanish

Paid plans start at $23.99 a month, or about $12.99 a month billed yearly, for 300,000 words (pricing). People look for alternatives when they need more languages, a different price, a tool that also rewrites, or better results on text that went through a humanizer.

At a glance

Pangram

Pangram is the detector to beat in independent research.

Strengths:

• Came out ahead of GPTZero, Originality.ai and RoBERTa in a University of Chicago study, with almost no false positives or misses on medium and long passages
• In a 2026 study from Vrije Universiteit Brussel, it was the only one of four detectors to catch fully AI-written papers, where GPTZero, Copyleaks and Turnitin failed
• Detects text that went through a humanizer, in 20+ languages
• An API at $0.05 per 100 words

Weak spots:

• The free tier is 3 scans a day
• Individual is $20 a month for 300,000 words

Best for: Anyone for whom accuracy matters more than price.

Originality.ai

Originality.ai is built for publishers and content teams.

Strengths:

• Pro is $14.95 a month, or $12.95 billed yearly, for 2,000 credits (200,000 words)
• Plagiarism, fact checking and readability in the same tool
• 30 languages, a Chrome extension, bulk scans and an API on Enterprise

Weak spots:

• Its pricing page describes the free tier two different ways
• Deeper scan modes use up to 50 credits per 100 words

Best for: Editors who check freelance and agency content.

Copyleaks

Copyleaks suits organisations and anyone working across languages.

Strengths:

• Up to 25,000 characters per scan without logging in
• AI detection in 30+ languages, plagiarism checking in 100+
• Browser extensions, a Google Docs add-on and AI image detection

Weak spots:

• Personal is $16.99 a month, or about $13.99 billed yearly, for 25,000 words
• In the 2026 Brussels study it missed the fully AI-written papers

Best for: Schools and companies with multilingual content.

Grammarly

Grammarly's AI Detector and humanizer sit inside the writing assistant many people already use. GPTZero and Grammarly now belong to the same company.

Strengths:

• A free web detector that takes up to 25,000 characters
• Works in Google Docs, Word, browsers and on desktop and mobile
• Authorship reports that show how a document was written

Weak spots:

• Detection inside Docs and Word needs Pro, at $30 a month or $144 a year
• Grammarly says its score "should not be used as an objective source of truth", and that text rewritten by its own humanizer will likely be flagged

Best for: People who already write in Grammarly.

QuillBot and Scribbr

QuillBot and Scribbr belong to the same company, Learneo.

Strengths:

• Free checks of up to 1,200 words per scan; Scribbr needs no account
• QuillBot also paraphrases and humanizes

Weak spots:

• QuillBot's Premium price depends on your country; in the US it is about $9.16 a month billed yearly on the web, and $19.99 a month in the App Store
• Scribbr's own ranking of AI detectors puts its own tool first

Best for: Free, occasional checks of shorter texts.

ZeroGPT

ZeroGPT is free and fast, and it is the tool most often confused with GPTZero.

Strengths:

• 15,000 characters per check for free
• Many extra tools: humanizer, paraphraser, plagiarism, image and video detection

Weak spots:

• A history of flagging human writing: it labelled part of the US Constitution as AI-generated, and in a 2024 test rated a Declaration of Independence excerpt 97.93% AI
• Paid plans from $14.99 a month

Best for: A quick, informal check. Do not rely on it for anything with consequences.

RealWrite (our product)

RealWrite's AI Detector is built for writers checking their own drafts.

Strengths:

• 500 detector words every day on a free account, 100 words without one
• An explanation for each flagged sentence, such as uniform sentence length, stock transitions or hedging, with a suggested fix
• A humanizer in the same place, so you can rewrite the flagged sentences and check again
• An iPhone app on the same account

Weak spots:

• Not yet included in the independent studies above
• No plagiarism check, no LMS integration and no browser extension
• Plans start at $14.99 a month ($9.99 billed yearly)

Best for: Writers who want to know why a draft reads as AI and fix it, rather than get a single number.

What independent studies found

• University of Chicago (2025): almost 2,000 passages from four AI models, some rewritten by the StealthGPT humanizer. Pangram had almost no errors; GPTZero missed about half of the humanized text. (paper)
• Vrije Universiteit Brussel (2026): 160 papers, including 40 theses by non-native English writers. All four detectors labelled the human texts correctly. On fully AI-written papers, only Pangram succeeded. (paper)
• Stanford (2023): seven detectors, including GPTZero and ZeroGPT, flagged on average 61% of essays by non-native English speakers as AI. (paper)

Detectors have improved since 2023, but they still disagree with each other and change with every update. Our guide to AI detector false positives explains why.

How to choose

1. Who decides? If your school or client uses a specific detector, that is the one that counts. Check with it, not only with others.
2. What do you need besides a score? Plagiarism checks, integrations, languages and explanations differ a lot.
3. How often? For a few checks a week, a free tier is enough. For daily use, compare words per dollar.
4. What happens next? If a draft is flagged, a detector that shows which sentences and why saves you time.

The bottom line

GPTZero is a good detector with a generous free plan. Pangram has the strongest independent results. Originality.ai and Copyleaks suit publishers and organisations. Grammarly, QuillBot and Scribbr are convenient free options. ZeroGPT is a different tool with a weaker record. RealWrite explains each flagged sentence and lets you fix it in the same place.

Whatever you use, treat the score as one piece of evidence. For a wider comparison of detectors, see the best AI detectors in 2026.