Side by side
| PICK | FREE LIMIT | VERDICT | NEED |
|---|---|---|---|
| GPTZero | 10,000 words a month on the free plan | Start here | Free every month with no payment details |
| Pangram | 20 checks a day after sign-up | Best for teachers checking student work | Lowest risk of a false flag |
| Copyleaks | Up to 25,000 characters per scan without logging in | Best for a single long essay | One check right now, no account |
| Copyleaks | AI detection in 30+ languages | Widest language list here | Non-English text |
| Turnitin | Institutional licenses only | Ask your school; students cannot see the report | The tool your instructor uses |
| None on its own | Not applicable | Use detector output only alongside drafts and a conversation | Deciding a misconduct case |
Our picks in detail
GPTZero
Best overall free plan; 10,000 words a month and no-account scans
- Best for: students checking a draft and teachers screening a few essays a month.
- Main limitation: GPTZero's FAQ says the majority of its training data is English prose written by adults and that it is not trained on text heavily modified after generation. Since 30 September 2026 it has been part of Superhuman, which also owns Grammarly.
GPTZero's free plan allows 10,000 words a month, according to GPTZero's pricing page checked on 23 October 2026.
Pangram
Best evidence on false positives; 20 free checks a day
- Best for: teachers, editors and reviewers who want the lowest chance of flagging honest work.
- Main limitation: in Epoch AI's test, Pangram missed 10.1% of AI passages written to imitate a specific author. Plagiarism checks and extra credits need a subscription.
Pangram flagged 0 of 495 human-written passages as AI in Epoch AI's detector test published 15 July 2026.
Copyleaks
Largest no-login scan; 30+ languages
- Best for: a single long essay checked right away, or text in a language other than English.
- Main limitation: the free account's extra monthly credits are Not listed, and scans feed the Shared Data Hub, a library of user-submitted documents, unless you opt out. Copyleaks states a 0.03% false positive rate on its AI detector page and 0.30% at the default setting on its testing methodology page; both are vendor claims, checked 25 October 2026.
Copyleaks scans up to 25,000 characters for free without an account, according to its AI detector page checked on 23 October 2026.
Turnitin
Free to you only through your school; hidden from students
- Best for: students and instructors at schools that already license Turnitin Originality.
- Main limitation: Turnitin's AI writing FAQ says the AI indicator and report are not visible to students; an instructor can share a PDF.
Turnitin does not sell individual licenses, according to its help center article checked on 23 October 2026.
Reviewed 23 October 2026 against GPTZero, Pangram, Copyleaks and Turnitin pricing, FAQ and help pages, and three published detector evaluations.
Our pick
GPTZero wins because it has the largest documented free monthly allowance of any detector here and keeps its free plan open to anyone. GPTZero's pricing page says the free plan covers up to 10,000 words a month and includes its Chrome extension, and a scan of up to 10,000 characters needs no account at all. In Epoch AI's July 2026 test of three detectors, GPTZero flagged none of 495 human-written passages as AI. The trade-off: the free tier gives a basic scan, and the advanced features sit on paid plans.
What "free" means for an AI detector
Free AI detectors come in two forms, and the difference decides whether a tool is completely free for you:
- A free plan with a monthly or daily cap. GPTZero (10,000 words a month) and Pangram (20 checks a day) fall here. You can use them every month without paying.
- A no-account scan. GPTZero accepts scans up to 10,000 characters without sign-up, and Copyleaks up to 25,000 characters. Nothing is stored in an account, and limits per scan are tighter.
Turnitin is a third case. Its help center says it does not sell individual licenses or single-use subscriptions, so it costs a student nothing only when the school pays.
Pangram offers twenty free checks a day after sign-up, according to Pangram's FAQ on its homepage checked on 23 October 2026.
What independent tests say about free detectors
No AI detector score should be the only evidence in a misconduct case.
Published tests evaluate each vendor's detector rather than a specific plan, so they are the best available guide to a free scan. Three sources shape this ranking:
- Current detectors rarely flag plain human text. Epoch AI found GPTZero and Pangram flagged none of 495 human passages (July 2026).
- One tool met a strict cap. A 2025 NBER working paper by Jabarian and Imas found Pangram was the only detector tested to keep false positives at or under 0.5% without sacrificing accuracy.
- Older tests found bias. Liang and colleagues found seven detectors, including GPTZero, misclassified non-native English writing as AI-generated, with an average false positive rate of 61.22% (Patterns, 2023).
The 2023 study covered older versions, and vendors have retrained since. The pattern still matters: short and formulaic texts produce the least reliable results, and a free scan of one paragraph says less than a paid scan of a full essay. Our guide to AI detector false positives explains what to do if you are flagged, and our explainer on how AI detectors work covers why scores vary.
Where free AI detectors fall short
No free plan gives everything. GPTZero's free tier is a basic scan; the advanced features are paid. Pangram's free plan needs an account and leaves out plagiarism checks. Copyleaks' no-login scan is generous per check, but the free account's monthly credits are Not listed. Free tools also change their limits often, which is why this page lists the date each limit was read.
If you need volume, one low-cost paid step is Copyleaks Personal at USD 13.99 a month billed annually. Our GPTZero alternatives ranking compares paid plans in detail.
How we picked
- We compared each detector's documented free allowance, sign-up rules, per-scan limits, languages and the cost of the first paid step, using vendor pricing, FAQ and help pages read on 23 October 2026, and weighted independent false positive evidence from Epoch AI (495 human passages, July 2026) and Jabarian and Imas (NBER, 2025). Both tests used fixed corpora that may not match your writing, and Epoch counted only a clean "AI" verdict as a flag. That rule leaves out ZeroGPT, whose site also offers a humanizer; our ZeroGPT vs GPTZero comparison and ZeroGPT review cover its free detector. Our full method is on the HumanRank ranking methodology page.
How to choose
How to choose
- Decide who is checking: a student before submission, or a teacher reviewing someone else's work.
- If you are a student at a Turnitin school, remember you cannot see Turnitin's AI report, so check drafts with GPTZero or Pangram. Our guide on whether Turnitin checks for AI explains what instructors see.
- Run the same 300-word or longer passage through GPTZero, Pangram and Copyleaks on the same day.
- Include a passage you wrote yourself. If a tool flags it, weigh that tool's score lightly.
- Keep drafts and version history for anything you submit, whatever the score.
- Write down how a flag will be used before the first scan.
For the full paid field, see our AI detector rankings, the GPTZero review, the Copyleaks review and GPTZero vs Turnitin. Teachers can start with our guide for educators.
Questions people ask
What is the best completely free AI detector?
GPTZero, with 10,000 free words a month and no payment details. Pangram is the pick if false positives worry you most, with 20 free checks a day.
Is there a free AI detector with no sign-up?
Yes. Copyleaks scans up to 25,000 characters without an account, and GPTZero scans up to 10,000 characters before asking you to sign up.
Is GPTZero free?
Yes, up to 10,000 words a month on the free plan, with paid plans for more words and features.
Is Turnitin available for free?
Only through a school or organization that licenses it. Turnitin does not sell individual licenses, and students cannot see its AI report unless an instructor shares it.
Are free AI detectors accurate?
No test has checked free tiers on their own. GPTZero and Pangram flagged no human passages in Epoch AI's 2026 test, but every detector misses some AI text.
Which free AI detector supports the most languages?
Copyleaks, with AI detection in 30+ languages. Pangram lists more than 20.
Can a free AI detector prove a student used AI?
No. GPTZero's own FAQ says results should not be used to punish students, and every detector makes errors.
Sources
- [1]GPTZero's pricing page gptzero.me · 23 Oct 2026
- [2]July 2026 test of three detectors epoch.ai · 23 Oct 2026
- [3]help center helpcenter.turnitin.com · 23 Oct 2026
- [4]FAQ gptzero.me · 23 Oct 2026
- [5]Pangram pricing page pangram.com · 23 Oct 2026
- [6]homepage pangram.com · 23 Oct 2026
- [7]AI detector page copyleaks.com · 23 Oct 2026
- [8]testing methodology page copyleaks.com · 23 Oct 2026
- [9]Copyleaks AI detector page copyleaks.com · 23 Oct 2026
- [10]Copyleaks pricing page copyleaks.com · 23 Oct 2026
- [11]AI writing FAQ guides.turnitin.com · 23 Oct 2026
- [12]2025 NBER working paper by Jabarian and Imas nber.org · 23 Oct 2026
- [13]misclassified non-native English writing as AI-generated arxiv.org · 23 Oct 2026