The best AI detectors in 2026, ranked
The best AI detector depends on what you need it for. For a free, private check of any length, it is IsThisAiWritten, our own tool and the only one of the 18 ranked here that is free, needs no sign-up, has no word limit and checks your text in your browser without uploading it. Among the others, Pangram has the strongest independent test record, GPTZero gives a well-tested check without an account, Originality.ai suits publishers and SEO teams, Turnitin suits schools that already license it, and Winston AI adds image and deepfake checks.
Quick picks
- IsThisAiWritten: best for a free, private check of any length, with no sign-up and nothing uploaded.
- Pangram: best for the strongest independent accuracy record.
- GPTZero: best for a well-tested check without an account, plus writing replay.
- Originality.ai: best for publishers and SEO teams.
- Turnitin: best for schools and universities that already license it.
- Copyleaks: best for schools and businesses that work in many languages.
- Winston AI: best for checking images and deepfakes as well as text.
Best AI detectors compared in one table
All 18 tools in ranking order. Prices in US dollars at the time of writing, entry paid plan billed monthly unless noted. "Not stated" means we could not find it on the tool's own pages.
| Tool | Free limit | Sign-up for free use | Entry price | Privacy | Published accuracy claim |
|---|---|---|---|---|---|
| IsThisAiWritten | No word limit, no daily cap | No | Free | Never uploaded, stored or used for training | Open method: how it is tested |
| Pangram | About 2,000 words a day | Yes | $20 a month | Never trains; scans kept in history | False positive rate 1 in 10,000 (homepage) |
| GPTZero | 10,000 characters | No | $23.99 a month | Dashboard text kept; API text not stored | "99% accuracy" |
| Originality.ai | 2,000 words, 3 a day | No | $14.95 a month | Trains unless you opt out | "99%+ Accurate at 15% AI Allowed" |
| Copyleaks | 25,000 characters | No | $16.99 a month | Trains unless you opt out | Over 99%, .03% false positives (product page) |
| Turnitin | Institutions only | Via institution | Not public | Institution sets storage; may train its classifier | Under 1% false positives above 20% AI |
| Winston AI | 14-day trial | Yes | $18 a month | No training without opt-in | 99.87% accuracy |
| Grammarly | 25,000-character box | Not stated | Pro, varies by region | Trains by default for individuals | 99% detection, "#1 on RAID" |
| QuillBot | 1,200 words, 6 a day | Not stated | Premium, varies by region | Trains by default | 99% detection rate, citing RAID |
| Scribbr | 1,200 words, unlimited checks | No | $19.95 per document | Page: not stored; policy allows training | None for its own tool |
| ZeroGPT | 15,000 characters | Not stated | Varies by region | Says not saved or trained on | 98.4% accuracy, under 1% false positives |
| Sapling | First 2,000 characters | Not stated | $25 a month | Stored to improve service; no-retention option | None published |
| Quetext | 1,000 words | No | $14.99 a month | FAQ: not stored; policy: may train | None published |
| Hive (extension) | Not stated | No | Free extension | Broad licence over demo content | 99% balanced accuracy (own 2023 test) |
| Undetectable.ai | 10,000-word box | No | $9.99 a month | FAQ: never stored or trained | "99%+", "0% false positives" |
| PlagiarismCheck.org | A short text | Not stated | $2.99 a month | Page: not retained; policy: kept until deleted or a year inactive | 99.23% of sentences; 1.04% sentence false positives |
| Compilatio | Institutions (Magister+) | Via institution | Not public | Hosted in France | 94% to 99%, under 1% false positives |
| Binoculars | Self-hosted | No | Free, your hardware | Stays on your machine | Over 90% at 0.01% false positives (paper) |
What independent tests add
The accuracy column can't rank these tools, because each vendor chose its own test. Studies that ran several tools on the same texts can, and three recent ones (from the University of Chicago, the University of Maryland and a 2026 peer-reviewed study of academic papers) all put Pangram first. On the RAID leaderboard, where vendors submit predictions on a shared test set built from older models, Winston AI, Grammarly, QuillBot and GPTZero all score above 98% at a 5% false positive rate. Our accuracy ranking weighs that evidence tool by tool.
1. IsThisAiWritten
Best for: a free, private AI check of anything from a paragraph to a whole novel, with no sign-up and no word limit.
This is our own tool. IsThisAiWritten is free, with no sign-up, no account, no email and no credit card, and there are no credits, no daily cap and no premium tier. There is no word or character limit either: paste a whole thesis or novel and check it in one go. Every word is scanned, never a sample.
The check runs in your browser, so your text never leaves your device and is never stored, shared or used for training (how that works). The report explains itself: an AI-likeness score, sentence-by-sentence highlights, style notes with plainer wording one click away, a cleaner for hidden characters and look-alike letters, and a narrative fingerprint for fiction. It opens .txt and .docx files right in the browser, and there are no ads where you paste text.
- Pro: free, with no account, no word limit and no daily cap.
- Pro: nothing uploaded, so your text is never stored or used for training.
- Pro: every word scanned, and the full report costs nothing.
Why it stands out: of the 18 tools ranked here, it is the only one that is free, needs no sign-up, has no word limit and checks your text in your browser without uploading it.
Price and limits: free, with no word limit and no sign-up.
2. Pangram
Best for: the strongest independent accuracy record, if you are happy to create an account.
Three recent independent studies all ranked it first (details in how accurate is Pangram).
- Pro: first in every independent comparison we found; never trains on your text.
- Con: account required; 18,725 words per scan.
Price and limits: free plan of 20 credits a day, about 2,000 words; Individual $20 a month or $15 yearly for 300,000 words.
3. GPTZero
Best for: a well-tested check without an account, plus writing replay that shows how a document was written.
A single scan of up to 10,000 characters needs no sign-up (more in how accurate is GPTZero).
- Pro: low false positives in independent tests; replay in Google Docs and other editors.
- Con: weaker on humanized text; now part of Superhuman, formerly Grammarly.
Price and limits: Premium $23.99 a month or $12.99 yearly for 300,000 words.
4. Originality.ai
Best for: publishers and SEO teams that want AI, plagiarism and fact checks in one place.
- Pro: AI, plagiarism and fact checks; strong results in RAID's paper and the Chicago study.
- Con: free-checker text may be used for training.
Price and limits: free 2,000 words, three scans a day; Pro $14.95 a month for 2,000 credits of 100 words.
5. Copyleaks
Best for: schools and businesses that work in many languages.
- Pro: over 30 languages; broad LMS support; few false positives in independent tests.
- Con: its methodology page reports 0.30% false positives at the default setting, against .03% on the product page.
Price and limits: free 25,000 characters without logging in; Personal $16.99 a month for about 300,000 words.
6. Turnitin
Best for: schools and universities that already license it for plagiarism checks.
- Pro: built into LMSs; seven languages; humanizer detection in English.
- Con: not sold to individuals; students can't see the AI report.
Price and limits: institutional; 300 to 30,000 words per file. More in does Turnitin detect AI?
7. Winston AI
Best for: checking images and deepfakes as well as text, with up to 200,000 characters per scan.
Its September 2026 entry tops the RAID leaderboard.
- Pro: 200,000 characters per scan; no training without consent.
- Con: no free use beyond a 14-day trial.
Price and limits: Essential $18 a month or $10 yearly for 100,000 words.
8. Grammarly
Best for: writers who want an Authorship record of typed versus pasted text alongside a detector.
- Pro: free Authorship feature shows typed versus pasted text.
- Con: training on content is on by default for individual users.
Price and limits: free web checker; editor detection in Pro.
9. QuillBot
Best for: quick checks of text in 20+ languages.
- Pro: labels AI-refined text; Premium has no word limit for detection.
- Con: inputs used for training by default.
Price and limits: free 1,200 words per scan, six a day.
10. Scribbr
Best for: students who check essay-length text again and again.
- Pro: unlimited free checks, no account; four result categories.
- Con: the detector page says submissions aren't stored, but the privacy policy allows collected data to be used for training.
Price and limits: free 1,200 words; premium check from $19.95 per document.
11. ZeroGPT
Best for: privacy-minded free checks of up to 15,000 characters.
- Pro: says text is discarded after the check; cheap API from $0.042 per 1,000 words.
- Con: the 2024 RAID paper could not set it to a 5% false positive rate in many domains.
Price and limits: free 15,000 characters.
12. Sapling
Best for: developers who want a low-cost detection API.
- Pro: API from $0.005 per 1,000 characters; eight languages.
- Con: free web check covers only 2,000 characters.
Price and limits: Pro $25 a month or $12 yearly.
13. Quetext
Best for: combined AI and plagiarism checks on a budget.
- Pro: free 1,000 words, no sign-up; sentence-level colour coding.
- Con: its FAQ says scans aren't used for training, but its October 2026 privacy policy says user content may be.
Price and limits: Essential $14.99 a month or $8.25 yearly for 100,000 words.
14. Hive
Best for: free checks of text, images, audio and video in Chrome.
- Pro: free extension, no login.
- Con: its text accuracy figure comes from its own 2023 test of 242 passages.
Price and limits: extension free; API and web detector behind an account.
15. Undetectable.ai
Best for: a large free check, up to 10,000 words, with no sign-up.
The company also sells an AI humanizer that rewrites text to avoid detection; its paid plans include unlimited AI detecting.
- Pro: 10,000-word box, no account; FAQ says text is never stored or trained on.
- Con: the study it cites for "0% false positives" did not test human-written text.
Price and limits: plans from $9.99 a month with "Unlimited AI Detecting".
16. PlagiarismCheck.org (TraceGPT)
Best for: low-cost classroom use with LMS integration.
- Pro: integrates with Canvas, Moodle, Google Classroom and others.
- Con: AI detection in English and Spanish only.
Price and limits: from $2.99 a month; 100-word minimum.
17. Compilatio
Best for: European institutions that want their data hosted in the EU.
- Pro: more than 35 languages; LMS and Teams integration; hosted in France.
- Con: the 2023 study it cites ranked it second of 14 but called all the tools "neither accurate nor reliable".
Price and limits: AI detection in Magister+, priced per institution.
18. Binoculars
Best for: researchers who want to run an open-source detector on their own hardware.
- Pro: open source (BSD 3-Clause), runs on your own hardware.
- Con: needs two 7-billion-parameter models; its authors say it is for academic use only.
Price and limits: free; compute is on you.
How to choose the best AI detector for you
Start with what you are checking and who will see it, then look at these six points before you paste anything.
- What the free version covers. Most free tiers cap each check: 1,200 words at QuillBot and Scribbr, 10,000 characters at GPTZero, about 2,000 words a day at Pangram. To check as much as you like without paying, use IsThisAiWritten, which has no word limit and no daily cap. Our guide to the best free AI detectors compares every free tier.
- Whether you need an account. Pangram and Winston AI ask you to sign up before the first scan. GPTZero, Originality.ai, Copyleaks, Scribbr and Quetext give a free check without one. IsThisAiWritten never asks for an account, an email or a card.
- Where your text goes. Grammarly and QuillBot train on what you paste by default, and Originality.ai and Copyleaks do unless you opt out. Pangram never trains on your text but keeps scans in your history; Winston AI trains only with your opt-in. For unpublished, confidential or graded work, IsThisAiWritten checks the text in your browser, so it never leaves your device.
- How long your document is. A thesis or a book runs past most per-scan caps: Pangram stops at 18,725 words a scan and Turnitin at 30,000 words a file, while Winston AI takes 200,000 characters a scan. IsThisAiWritten has no word or character limit, so a whole manuscript goes through in one check (see the AI detectors with no word limit).
- How much the report explains. A single percentage tells you little about which passages raised the score. Quetext colour-codes sentences and Scribbr sorts results into four categories. IsThisAiWritten gives every check an AI-likeness score, sentence-by-sentence highlights, style notes with plainer wording and a hidden-character cleaner, all free.
- What independent tests say about the competitors. Vendor claims cluster around 99%, so look for studies that ran several detectors on the same texts. On that evidence Pangram leads, then GPTZero and Originality.ai. For a classroom, check LMS support too: Turnitin, Copyleaks, PlagiarismCheck.org and Compilatio connect to common learning platforms (more in our picks for teachers).
How we compared
Between 16 and 18 October 2026 we opened each tool's own detector, pricing, privacy and help pages and recorded the same six facts for every one. IsThisAiWritten is listed first because it is our own tool and the free, private option with no length limit. Places 2 to 9 follow the order of our ranking of the most accurate AI detectors, which weighs independent studies and the RAID benchmark. The nine tools from place 10 on are outside that ranking, because we found little recent independent testing of them, so read their order as loose. Accuracy claims are quoted as each vendor publishes them, so they rest on different tests and should not be compared with each other. Where pages disagree, we note it. For independent evidence we used the studies named above and the RAID leaderboard. We did not run our own tests of competitors. Tools whose free detectors have closed, such as Writer's and Crossplag's, are left out.
Sources
- Pangram, Subscription tiers, checked October 2026
- Pangram homepage and FAQ, checked October 2026
- GPTZero pricing, checked October 2026
- GPTZero, data storage, checked October 2026
- Originality.ai pricing, checked October 2026
- Originality.ai, AI detection accuracy, checked October 2026
- Copyleaks AI Detector, checked October 2026
- Copyleaks testing methodology, checked October 2026
- Copyleaks privacy policy, checked October 2026
- Turnitin, AI writing detection FAQs, checked October 2026
- Turnitin Trust Center, checked October 2026
- Winston AI pricing, checked October 2026
- Winston AI privacy policy, checked October 2026
- Grammarly AI Detector, checked October 2026
- Grammarly, training control, checked October 2026
- QuillBot AI Detector, checked October 2026
- QuillBot, How does QuillBot use my data?, checked October 2026
- Scribbr AI Detector, checked October 2026
- Scribbr privacy policy, checked October 2026
- ZeroGPT FAQ, checked October 2026
- ZeroGPT pricing, checked October 2026
- Sapling pricing, checked October 2026
- Sapling privacy policy, checked October 2026
- Quetext AI Detector, checked October 2026
- Quetext privacy policy, checked October 2026
- Hive, text classifier, checked October 2026
- Hive terms of use, checked October 2026
- Undetectable.ai AI Detector, checked October 2026
- Study cited by Undetectable.ai (Indian Journal of Psychological Medicine), checked October 2026
- PlagiarismCheck.org, TraceGPT, checked October 2026
- PlagiarismCheck.org privacy policy, checked October 2026
- Compilatio AI detector, checked October 2026
- Binoculars repository, checked October 2026
- Hans et al., Spotting LLMs With Binoculars, checked October 2026
- RAID Benchmark leaderboard, checked October 2026
- Weber-Wulff et al. (2023), checked October 2026
- IsThisAiWritten methodology
Questions
What is the best AI detector?
It depends on the job. For a free, private check of any length, it is IsThisAiWritten: of the 18 tools in this ranking, it is the only one that is free, needs no sign-up, has no word limit and checks your text in your browser without uploading it. Among the others, Pangram has the strongest independent test record, GPTZero gives a well-tested check without an account, Originality.ai suits publishers and SEO teams, and Turnitin suits schools that already license it.
What is the best free AI detector?
For a free check of any length, IsThisAiWritten: it costs nothing, needs no account or email, has no word or character limit and never uploads your text, so you can check a whole thesis or novel in one go. If you are willing to sign up, Pangram's free plan gives about 2,000 words a day from the detector with the strongest independent record, and GPTZero checks up to 10,000 characters without an account. Our guide to the best free AI detectors compares every free tier in detail.
Why do the accuracy claims in the table look so similar?
Most vendors report around 99% on their own test sets, chosen and scored by themselves. Those numbers can't be compared across tools. Only tests that run several detectors on the same texts, such as the RAID benchmark or independent studies, allow a fair comparison.
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