Yes, GPTZero is free to use. Its pricing page says the free plan covers up to 10,000 words a month, and you can paste short text without an account. For scans over 10,000 characters GPTZero asks you to create a free account first. Paid plans raise the word allowance and add features such as its writing feedback.
GPTZero is one of the best known AI detectors, used by teachers, students and editors to check whether text was likely written by a model like ChatGPT. Here's what the free plan covers, what GPTZero says about its own accuracy, and how to make 10,000 words go further.
What GPTZero gives you for free
- A free plan covering up to 10,000 words a month, per GPTZero's pricing page FAQ.
- Paste and scan short text without signing up.
- A free account for any single scan over 10,000 characters.
- Its Chrome extension, which GPTZero says is included in the free plan built for education.
- Highlighted sentences, so you can see which parts look AI-written rather than just a score.
GPTZero also says its plagiarism checker is covered by the same free plan, up to 10,000 words a month.
Words vs characters: the limit people trip over
GPTZero uses two different measures, which is why people get confused. The monthly allowance is counted in words. The sign-up prompt is triggered by characters. A 10,000-character scan is only around 1,600 words of English, so a single long essay can push you into making a free account, and a few long documents use the month's 10,000 words quickly. A 5,000-word dissertation chapter, for example, is half the free month in one scan.
GPTZero paid plans
GPTZero's pricing page lists individual plans, a Professional Team plan and an API for developers. The team plan includes everything in the Professional plan per seat, shared team credits, unified billing and 500,000 words per member per month, with a minimum of 2 seats and card payment only. The page shows individual plan prices once you choose monthly or annual billing, so check it on the day you sign up.
What GPTZero says about its own accuracy
This is the part worth reading before you act on a score. GPTZero's own FAQ says no AI detector is fully accurate, that AI itself keeps changing, and that results shouldn't be used to punish or as the final verdict. It says accuracy improves with longer inputs, that document-level results are stronger than sentence-level ones, and that it's strongest on English prose. It fully supports English, German, Portuguese, French and Spanish.
So if you're a teacher, use a GPTZero result to start a conversation, not to decide a grade. If you're a student who's been flagged, ask to talk through your drafts and notes. I've written about the signals these tools look for in my guide on how to detect AI-written content.
How to use GPTZero for free
- Go to gptzero.me and paste your text into the box.
- Click Scan. For text over 10,000 characters, create a free account first.
- Read the highlighted sentences, not just the overall result.
- Install the free Chrome extension if you check Google Docs often.
- Save your monthly 10,000 words for full documents rather than rescanning small edits.
If you write with AI help and want the result to sound like you, my guide to AI essay writing tools explains how to keep your own voice in the draft.
How GPTZero decides if text is AI
GPTZero's FAQ explains the signals AI detectors look for. Perplexity asks whether the writing is predictable. Burstiness looks at how much sentence length and style vary, since people tend to mix short and long sentences more than models do. Style checks whether the tone is generic or repetitive. GPTZero says its own model weighs hundreds of factors on top of these, and gives document, sentence and word-level analysis.
It says it works across models including ChatGPT, Gemini, Claude, Llama and DeepSeek. Short or heavily edited passages are harder to judge, which is another reason to scan whole documents rather than a single paragraph.
Who uses GPTZero
GPTZero says it's founded in January 2023, has served more than 20 million users and is used in over 3,500 colleges. It also lists publishers, recruiters, copywriters and marketers among its users, and calls itself an official AI detector partner of the American Federation of Teachers.
Free GPTZero tools for writers
GPTZero isn't only for checking other people's work. Its site offers a free Google Docs add-on and free grammar checking and feedback. Its Chrome extension, Origin, lets you scan a whole web page in one click and shows typing pattern metrics in Google Docs. GPTZero pitches that last feature at students and writers who want to show their writing is their own, so they're not falsely accused of using AI.
If you write in Google Docs, keeping your version history is the simplest proof of how a piece came together, whichever tool your teacher or editor uses.
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My verdict: is GPTZero free?
Yes, for occasional checks. The free plan's 10,000 words a month covers a few essays or articles, and a free account removes the 10,000-character cap on a single scan. If you check work every day, a paid plan makes more sense. Whatever plan you use, follow GPTZero's own advice: treat the result as a signal, not a verdict.
Teachers and students often compare checkers, so see whether Turnitin is free.
Frequently asked questions
Is GPTZero free?
Yes. GPTZero's free plan covers up to 10,000 words a month, and you can scan short text without an account.
Do I need an account to use GPTZero?
Not for short text. GPTZero asks you to create a free account for scans over 10,000 characters.
How many words can I check free on GPTZero?
Up to 10,000 words a month on the free plan, according to GPTZero's pricing page.
Is GPTZero accurate?
GPTZero says no detector is fully accurate and results shouldn't be used to punish. Longer English text gives stronger results.
Does GPTZero have a Chrome extension?
Yes. GPTZero says its free plan built for education includes the Chrome extension.
What languages does GPTZero support?
GPTZero says it fully supports English, German, Portuguese, French and Spanish.
Does GPTZero check for plagiarism too?
Yes. GPTZero says its plagiarism checker is included in the free plan, which covers up to 10,000 words a month.
Can a GPTZero result prove someone used AI?
No. GPTZero itself says results shouldn't be used to punish or as the final verdict, and that no detector is fully accurate.
