AI text detectors compared: 18 tools side by side
AI text detectors compared in one place: 18 tools, side by side, on what you can check for free, whether you need an account, what it costs, what happens to your text and what accuracy each company claims. All facts are from the companies' own pages in October 2026. The accuracy column holds vendor claims, not test results, so read the notes on independent evidence underneath.
Quick picks. Free, private and unlimited: IsThisAiWritten. Strongest independent accuracy record: Pangram. Schools: Turnitin where licensed, otherwise Copyleaks or Pangram with their LMS integrations. A tested detector with no account: GPTZero.
AI text detectors compared in one table
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 limit | No | Free | Never uploaded | Open methodology: 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.
IsThisAiWritten
Best for: free, private checks of any length. It is our own tool.
- Pro: no account, no limit and every word scanned; runs in your browser, so the text is never uploaded; open methodology.
- Con: English only.
Price and limits: free; 50-word minimum.
Pangram
Best for: the highest accuracy on independent evidence.
- 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; Individual $20 a month or $15 yearly for 300,000 words.
GPTZero
Best for: a well-tested check with no account, plus writing replay.
- 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.
Originality.ai
Best for: publishers and SEO teams.
- 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: Pro $14.95 a month for 2,000 credits of 100 words.
Copyleaks
Best for: multilingual schools and businesses.
- 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: Personal $16.99 a month for about 300,000 words.
Turnitin
Best for: institutions already using it for plagiarism.
- 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.
Winston AI
Best for: text plus image and deepfake checks.
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.
Grammarly
Best for: writers who want Authorship records 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.
QuillBot
Best for: quick checks 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.
Scribbr
Best for: students running repeated checks.
- 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.
ZeroGPT
Best for: privacy-minded free checks.
- 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.
Sapling
Best for: developers.
- 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.
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.
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.
Undetectable.ai
Best for: a large free check 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".
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.
Compilatio
Best for: European institutions wanting EU hosting.
- Pro: more than 35 languages; LMS and Teams integration.
- 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.
Binoculars
Best for: researchers who want to self-host.
- 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 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 limit. After it come the eight tools from our accuracy ranking, in the same order, then the rest. 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 and open benchmark
Questions
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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