Which AI detectors share an owner? The ownership map from the vendor pages

QuillBot and Scribbr. Scribbr's about page, read 8 November 2026, says: "Today, Scribbr is proud to be a part of QuillBot, within the broader Learneo family of businesses. Together with LanguageTool, our three brands empower 56M people" (scribbr.com). QuillBot's own about page did not load on 8 or 9 November 2026, so the QuillBot card takes the Learneo line from its sister brand and says so. The two detectors are sold differently: Scribbr states unlimited free checks with no sign-up and QuillBot states 1,200 words per scan and 6 scans a day free, per the detector pages read 8 November 2026, and Scribbr has 1 study record (Walters 2023, DOI 10.1515/opis-2022-0158) while QuillBot has none. Whether the two run the same model is not stated on either page, and the index records nothing it cannot read.

Grammarly states it; GPTZero states a plan. Grammarly's AI detector page carries the footer "2026 (c) Superhuman Platform" and a Company menu listing Superhuman and GPTZero, and its Pro page offers Enterprise access "through Superhuman Go" (grammarly.com, read 8 November 2026). GPTZero's news post of 23 June 2026 says "GPTZero plans to join Superhuman", its privacy policy names GPTZero LLC as the legal entity, and its footer now lists Superhuman and Grammarly (gptzero.me, read 8 November 2026). The two cards therefore record a stated group for Grammarly and an announced plan for GPTZero; neither page read on 8 November 2026 states that the transaction has closed, so the index does not say it has. The pair differ sharply on the record: GPTZero has 11 study records, the most in the index (ranking by independent testing), and Grammarly has none.

The two Superhuman detectors are compared field by field on GPTZero vs Grammarly, added 9 November 2026: twelve study records against none, and two separate price lists under one platform owner.

The two Learneo detectors are compared field by field on Scribbr vs QuillBot, added 10 November 2026: one measured false positive rate against none, six languages against one, and no study that ran both.

TruthScan and Undetectable AI. The TruthScan site footer and its Terms of Service, last updated 27 August 2026, name "Undetectable Inc. dba TruthScan" with an address at 1309 Coffeen Ave., Sheridan, Wyoming, and the team page names Christian Perry as CEO, "an entrepreneur who previously founded Undetectable.ai" (truthscan.com/terms, read 9 November 2026). The Undetectable AI terms of use, last updated 1 January 2025, name "Undetectable Inc., doing business as Undetectable AI" under Idaho law, and its about page names the same founder (undetectable.ai/terms, read 9 November 2026). The two products are sold to different buyers: Undetectable AI is a free text check beside a humanizer marketed to score as human on detectors, and TruthScan leads with AI image and PDF detection for fraud teams, with text as one product of the suite (TruthScan card; Undetectable AI card). Neither page states whether the two text detectors share a model, and both state a 99%+ figure of their own with no indexed study behind either (claim vs evidence gap ranking).

Five cases, each one company. Copyleaks and Codeleaks are the text detector and the source code product of Copyleaks Inc, New York; Codeleaks has its own card because its fields differ (programming languages in place of natural languages, token metering, and an API whose AI code verdict was withdrawn on 16 December 2025 per the release notes, docs.copyleaks.com, read 9 November 2026). Grammarly and Grammarly Authorship are two features of one writing assistant, the second a process record rather than a classifier (grammarly.com/authorship, read 9 November 2026), and Turnitin Clarity is a paid add-on to Turnitin Feedback Studio from Turnitin, LLC (guides.turnitin.com, read 9 November 2026); both pairs have their own cards because the products differ, and the Superhuman and Turnitin rows above cover the owners. Turnitin's AI writing detection is sold inside Turnitin Originality and as "the AI writing add-on for iThenticate 2.0", both Turnitin products, per the capabilities FAQ read 8 November 2026 (guides.turnitin.com); iThenticate has no card because the detector is the same product under a second licence. Content Detector AI, added on 10 November 2026, is a lineage case rather than an ownership case: its archived page of 11 May 2026 states "It is powered by Content at Scale's AI Detector", the detector Weber-Wulff 2023 and Walters 2023 tested as Content at Scale and the index cards as BrandWell, and the live address now redirects to the same Moxby Mod as the BrandWell page (web.archive.org, read 9 November 2026); the archived footer names a different company in Alpharetta, Georgia, so the two cards share a detector engine by the archived page's statement and not a stated owner. Three more lineage rows joined on 10 November 2026 with the tenth wave, each sourced to the vendor's own page and none a shared owner: Monica's detector page says "We currently integrated 3 AI detection models, including GPTZero, CopyLeaks, and ZeroGPT", so the Monica card calls three other cards' engines under Butterfly Effect Pte. Ltd.'s name (monica.im/tools/ai-content-detector, read 10 November 2026); Passed.ai's archived home page says "We've partnered with the leader in AI Detection accuracy, Originality.ai" and its closing notice says the team has joined Originality.ai, so Fractal SAAS Inc.'s product used Originality AI Inc.'s engine and no page states that either company owns the other (web.archive.org, 7 June 2026, passed.ai, read 10 November 2026); and Trinka is "a fully owned product of Crimson AI Pvt. Ltd.", the company behind the Enago author-services brand, a parent-and-product line rather than two detectors under one owner (trinka.ai/privacypolicy, read 10 November 2026). Hive's detection APIs are now sold by Castle Global, Inc. under the Deploy name: every thehive.ai page carried the banner "Hive is now Deploy" on 8 November 2026, and pricing, privacy and terms are served from deploy.com (deploy.com, read 8 November 2026). The card keeps the Hive name because the vendor's own detector pages still use it.

Eighteen of the first twenty-two cards name a single company, project or lab and no parent, and the index leaves it there; of the sixteen cards added on 9 November 2026, twelve do the same (AI or Not, BrandWell, Compilatio, Deepware, Quetext, Sensity, Sightengine, Smodin, Surfer, SynthID, Writer and DetectGPT, the last a Stanford research release with no company at all), two belong to groups already in the table (Grammarly Authorship, Turnitin Clarity) and two form the third pair (TruthScan, Undetectable AI). The GPT-2 Output Detector and GLTR are open-source releases, from OpenAI in 2019 and from the MIT-IBM Watson AI Lab with HarvardNLP, with no company selling them (Hugging Face; github.com, read 9 November 2026). Several vendors name a registered address and nothing above it: Phrasly, LLC and DevZero Inc. (AIDetectPlus) in Dover, Delaware; Olive Works LLC (ZeroGPT) in Wyoming; GM Appdev Limited (JustDone) in Limassol; CQC Pvt. Ltd. (Codequiry) in Chennai; Originality AI Inc. in Collingwood, Ontario, all from the terms or privacy pages read 8 and 9 November 2026. A registered address is a legal fact about one company; the index does not read ownership into it. WasItAI publishes no legal entity at all (wasitai.com, read 9 November 2026). Of the twelve cards added on 10 November 2026 in the tenth wave, nine name one company, lab or author group and no parent (Monica, Trinka, StealthWriter, Wordtune, Check For AI, Passed.ai, ElevenLabs, Intel and Ircam Amplify), two are research releases with no company (Binoculars, Deepfake-O-Meter) and one, Writefull, names an affiliate group (Digital Science) without a parent statement; none forms a new shared-owner pair.

Ownership matters to a reader for two reasons the index can show. A shared owner can mean a shared model, and the record is silent on that for both pairs. And a shared owner can mean a shared data policy: Scribbr says submissions are not stored and QuillBot's retention statement did not load (data retention ranking); GPTZero stores dashboard inputs and Grammarly's retention field is empty, per the policies read 8 November 2026.

Ownership changes over time as well as across brands: the launch year ranking, added 10 November 2026, dates each card's launch beside the renames, acquisitions and closures the cards record (Content at Scale to BrandWell, Optic to AI or Not, Hiya's purchase of Loccus.ai, Passed.ai's team joining Originality.ai), and the nine cards of the eleventh wave added nine more owners, none shared: Neuraltext (GPT Radar), Toolka Web Services (Grammica), IvyPanda, Ninety ApS (SEO.ai), Empirical Resolution Inc. (AI Writing Check), the RADAR and Ghostbuster research groups, Hiya, Inc. and McAfee, LLC, each read 10 November 2026 on the page its card cites.

All read 8 November 2026 unless a later date is shown.

• Scribbr about page: https://www.scribbr.com/about-us/
• Grammarly AI detector: https://www.grammarly.com/ai-detector
• GPTZero, Preserving what's human (23 June 2026): https://gptzero.me/news/preserving-whats-human
• Turnitin AI writing detection FAQs: https://guides.turnitin.com/hc/en-us/articles/28477544839821
• Turnitin AI writing: https://www.turnitin.com/solutions/topics/ai-writing/
• Deploy privacy policy (Hive): https://deploy.com/privacy
• Copyleaks privacy policy: https://copyleaks.com/privacy-policy
• Originality.ai privacy policy: https://originality.ai/privacy-policy
• Pangram about: https://www.pangram.com/about-us
• Phrasly terms: https://phrasly.ai/terms
• Sapling terms: https://sapling.ai/tos
• JustDone AI detector: https://justdone.com/ai-detector
• ZeroGPT privacy policy: https://www.zerogpt.com/privacy-policy
• Winston AI privacy policy: https://gowinston.ai/privacy-policy/
• Proofademic terms of service: https://proofademic.ai/terms-of-service/
• Walter Writes terms of service: https://walterwrites.ai/terms-of-service/
• AIDetectPlus about: https://aidetectplus.com/about (read 9 November 2026)
• Codequiry privacy policy: https://codequiry.com/privacy-policy (read 9 November 2026)
• GLTR repository: https://github.com/HendrikStrobelt/detecting-fake-text (read 9 November 2026)
• GPT-2 Output Detector demo: https://openai-openai-detector.hf.space/ (read 9 November 2026)
• WasItAI privacy policy: https://wasitai.com/privacy (read 9 November 2026)
• Reality Defender privacy policy: https://www.realitydefender.com/t-c/privacy-policy (read 9 November 2026)
• Walters 2023: https://doi.org/10.1515/opis-2022-0158
• Ha, Passananti et al. 2024: https://arxiv.org/abs/2402.03214 (read 9 November 2026)
• TruthScan terms of service: https://truthscan.com/terms (read 9 November 2026)
• Undetectable AI terms of use: https://undetectable.ai/terms (read 9 November 2026)
• Grammarly Authorship: https://www.grammarly.com/authorship (read 9 November 2026)
• Turnitin Clarity administrator FAQs: https://guides.turnitin.com/hc/en-us/articles/37670935742989-FAQs-for-administrators-using-Turnitin-Clarity (read 9 November 2026)
• BrandWell terms: https://brandwell.ai/terms/ (read 9 November 2026)
• Compilatio legal notices: https://www.compilatio.net/en/legal-notices/ (read 9 November 2026)
• Smodin about: https://smodin.io/about (read 9 November 2026)
• Quetext privacy policy: https://www.quetext.com/privacy-policy (read 9 November 2026)
• Sightengine legal notice: https://sightengine.com/policies/legal-notice (read 9 November 2026)
• Sensity terms and conditions: https://sensity.ai/terms-and-conditions/ (read 9 November 2026)
• Deepware about: https://deepware.ai/us/about/index.html (read 9 November 2026)
• DetectGPT repository: https://github.com/eric-mitchell/detect-gpt (read 9 November 2026)

Revision log: 2026-11-09: page created from the ownership field of 22 cards; 2026-11-09: sixteen cards of the third and fourth waves added, TruthScan and Undetectable AI recorded as the third shared owner (Undetectable Inc.); 2026-11-09: four wave 5 cards added, Copyleaks and Codeleaks recorded as one company with two cards, Illuminarty, Pindrop Pulse and Resemble Detect each naming a single company; 2026-11-10: nine ninth-wave cards added to the ownership table (Imagga held); Content Detector AI recorded as a Content at Scale (BrandWell) lineage case from the archived page, not a shared owner; 2026-11-10: Scribbr vs QuillBot comparison linked; 2026-11-10: twelve tenth-wave ownership rows added; Monica (three third-party engines), Passed.ai (Originality.ai engine) and Trinka (Crimson AI, Enago) recorded as sourced lineage rows, not shared-owner rows; 2026-11-10: nine eleventh-wave owners noted, none shared; launch year ranking linked