Checks content for AI writing, plagiarism and factual errors before you publish it.
Writing & Translation
GPTZero
Checks whether text was written by AI, with plagiarism and citation checks too.
4.2our rating
FreemiumFrom $0Works with Claude Code
Quick take
- The best-known AI detector. Paste text and it scores how AI-written it looks, sentence by sentence.
- Free covers 10,000 words a month, which is plenty for checking the odd document.
- Premium is $12.99 a month billed yearly for 300,000 words, and adds the advanced scan, plagiarism checks and downloadable reports.
- Like every detector it gets it wrong sometimes, mostly by flagging human writing. Never treat a score as proof on its own.
- Built mainly for schools, but the API and bulk file scans suit businesses checking a lot of content.
What is GPTZero?
GPTZero tells you how likely a piece of text is to have been written by AI. Paste text or upload a file and it gives an overall score, and highlights the sentences that look most AI-written. It also checks for plagiarism, flags made-up citations, and has a Chrome extension that replays how a Google Doc was written so a writer can show they typed it themselves.
It started as a tool for teachers and is still the best-known detector in schools, with Canvas and Google Classroom integrations and an official partnership with the American Federation of Teachers. Businesses use it to check freelance work, job applications and content before it goes live, and there's an API for running checks from your own systems.
The catch: no AI detector is proof. Every detector, GPTZero included, sometimes flags human writing as AI, especially short or very formal text and writing by people using English as a second language. Light editing of AI text can also slip past. Use a score to start a conversation, never to settle one.
Who's using it, and who it's for
- Teachers
- Editors
- Content agencies
- Recruiters
- Students
Teachers, editors and business owners who want a second opinion on whether writing they've been handed came from AI.
Key features
AI detection
Scores how likely text is to be AI-written and highlights the sentences that look most like ChatGPT, Claude or Gemini.
Plagiarism check
Compares your text with web pages and published work and shows any matches.
Writing replay
A Chrome extension replays how a Google Doc was written, so you can see whether it was typed or pasted in.
Citation and hallucination check
Flags sources and references that look made up, which AI tools still do.
Batch scans
Upload up to 50 files at once on Premium, or 250 on Professional.
API and school integrations
Run checks from your own systems, or inside Canvas and Google Classroom.
How we rate it
4.2 / 5
Our rating
From using the tool ourselves. The average of the five scores.
- Ease of use
- 4.5
- Features
- 4.5
- Output quality
- 3.5
- Value for money
- 4.0
- Speed & reliability
- 4.5
How quickly someone non-technical gets value from it.
How completely it covers its own job, and how well the pieces fit together.
How good the results are before you fix them.
What you get for the price, including the free plan.
How fast it is and how often it falls over.
GPTZero pricing
Free
$0
Checking the odd document.
- 10,000 words a month
- Basic AI scan
- Chrome extension
- Our pick
Premium
$23.99/mo, or $12.99/mo billed yearly
Teachers and editors checking work every week.
- 300,000 words a month
- Advanced AI scan and multilingual detection
- Plagiarism checker
- Downloadable AI reports
- Batch upload of 50 files
Professional
$45.99/mo, or $24.99/mo billed yearly
Agencies and heavy users scanning lots of files.
- 500,000 words a month, with overage up to 2 million
- Batch upload of 250 files
- Page-by-page scanning
- Longer scans of up to 150,000 characters
Team
Professional price per seat, 2 seats minimum
Schools and businesses buying for a group.
- Everything in Professional for each person
- Shared credits and one bill
- Seat management
Which plan should you pick?
Start on Free. If you check more than a few documents a week, Premium on yearly billing is the sweet spot. Professional only makes sense if you scan big batches of files.
Prices in USD unless noted, checked 3 November 2026. Vendors change plans often, so confirm on their site before you buy.
Best use cases
Ways GPTZero can slot into your week.
- 1
Check commissioned content
Run every article from a freelancer through GPTZero before you pay, and ask about anything it flags.
- 2
Screen job applications
See whether cover letters and written test answers look AI-written before you shortlist.
- 3
Catch fake references
Check a report or white paper for citations that don't exist before you publish it.
- 4
Protect your own work
Write in Google Docs with the extension on, so you have a replay to show if anyone questions your writing.
How it fits your tech stack
It sits between writing and publishing. Drafts come from your writers or AI tools, GPTZero checks them, then they go out. Pair it with Grammarly for polish, or use Originality.ai if your focus is SEO content at scale.
Connects to
- Google Chrome
- Google Docs
- Canvas
- Google Classroom
Pros and cons
Pros
- Clear sentence-level highlights, so you see exactly what looks AI-written
- Generous free plan for occasional checks
- Writing replay gives honest writers a way to prove their work
- Flags made-up citations, which most detectors don't
- API and batch scans for larger volumes
Cons
- False positives happen, and short or formal writing gets flagged more often
- Edited or reworded AI text can get past it
- The best scan and plagiarism checks need a paid plan
- Mostly designed around schools, so some features won't matter to a business
GPTZero alternatives
The closest alternatives to GPTZero in the library, best rated first.
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Grammarly
4.3
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DeepL
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Why it made the list
It's the most widely used AI writing detector, trusted by over 10 million teachers and students, with a free plan that covers occasional checks.
GPTZero FAQ
How much does GPTZero cost?
There's a free plan, and paid plans start at $0. Prices checked 3 November 2026 against GPTZero's pricing page.
Is GPTZero free?
Yes, GPTZero has a free option. Start on Free. If you check more than a few documents a week, Premium on yearly billing is the sweet spot. Professional only makes sense if you scan big batches of files.
What is GPTZero best for?
GPTZero is best for checking essays and assignments for AI writing, screening freelance or agency content and spotting made-up citations in reports. Teachers, editors and business owners who want a second opinion on whether writing they've been handed came from AI.
What are the best GPTZero alternatives?
The closest alternatives are Google Translate, Grammarly, Hemingway Editor and DeepL. Google Translate is best for quick translations of emails and messages.
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