SEO.ai AI Content Detector
Vendor SEO.AI (Ninety ApS) Official site seo.ai/tools/ai-content-detector How this card is sourced
Updated · AI Detector Index editors
SEO.ai's AI Content Detector called 12% of the 42 human-written papers AI in Walters 2023, the third-highest false positive rate of the 16 detectors in that study, while classifying 72% of the 126 documents correctly with 24% uncertain (DOI 10.1515/opis-2022-0158, Table 4, read 8 November 2026). The tool is a free page on seo.ai, an SEO platform operated by Ninety ApS of Kongens Lyngby, Denmark, business registration DK43096990 (seo.ai/privacy-policy, Effective April 10th, 2025, read 10 November 2026). Its page claims "an impressive 98.4% (accuracy rate)" for a tool that needs no login, and the same page's FAQ says AI detectors "aren't highly accurate" (seo.ai/tools/ai-content-detector, read 10 November 2026). The card is one of the text detectors in the detector index, and how this card is sourced explains how a 98.4% claim and a 72% study result are set beside each other.
What SEO.ai detects
| Field | Value | Source |
|---|---|---|
| Content types detected | Text | seo.ai/tools/ai-content-detector |
| Generators covered | ChatGPT, GPT-4, Bard, Claude, Gemini (Detect AI-generated content from ChatGPT, GPT-4, Bard, Claude, and Gemini in any language) | seo.ai/tools/ai-content-detector |
| Languages | Arabic, Basque, Bengali, Bulgarian, Catalan, Chinese, Croatian, Czech, Danish, Dutch, English, Estonian, Finnish, French, Galician, German, Hebrew, Hindi, Hungarian, Icelandic, Italian, Japanese, Kannada, Korean, Latvian, Lithuanian, Malay, Malayalam, Marathi, Norwegian, Polish, Portuguese, Punjabi, Romanian, Russian, Serbian, Slovak, Slovenian, Spanish, Swedish, Tamil, Telugu, Thai, Turkish, Ukrainian, Vietnamese (50 listed) | seo.ai/tools/ai-content-detector |
| Input limits | Paste-only web tool with no login (page title: Free AI Content Detector, Super Fast, No Login Required): the widget's counter reads N characters (Max 20000 allowed) and cuts the input at 20,000 characters (tools.seo.ai/build/AiContentDetector.js, read 10 November 2026), while the page's meta description says Check up to 25.000 characters of text. The result is a 1% to 100% AI probability (A score of 1% indicates human-made content, while a score nearing 100% suggests a high probability of being AI-generated) with four sub-scores the widget labels Prediction, Entropy, Perplexity and Diversity (the FAQ names Prediction, Entropy, Correlation and Perplexity). No file upload; the widget posts to tools.seo.ai/api/ai-detection, an undocumented endpoint with no public API page. | tools.seo.ai/build/AiContentDetector.js |
| Free tier | Free with no login and no stated quota: Free AI Content Detector, Super Fast, No Login Required; 20,000 characters per check as enforced by the widget. The paid plans price the SEO platform, under which the pricing page lists the detector as a Free Tool | seo.ai/tools/ai-content-detector |
| Data retention | Privacy Policy (Effective April 10th, 2025, Version 1.3), Data Retention: We retain personal information only as long as necessary to fulfill the purposes described above and comply with applicable legal obligations. Upon expiration of these purposes or at your request, information is securely deleted. The policy lists name, business email, company and payment details and data from Google integrations; it states nothing about text pasted into the free tools and no period. Terms 5.2.1 define User Content as texts, files, links, images, photos, audio, mixed media content submitted to the Solution. | seo.ai/privacy-policy |
| Ownership | SEO.AI operated by Ninety ApS, Diplomvej 381, 2800 Kongens Lyngby, Denmark, business registration number DK43096990 (Privacy Policy, Effective April 10th, 2025, Version 1.3; Terms, section 19). Terms 18.1: any dispute must be settled under Danish law, with the District Court in Copenhagen as the agreed venue. The detector is one of the site's Free AI SEO Tools beside a paid SEO platform; the Wayback index holds the detector at seo.ai/ai-content-detector from 3 October 2023 and at the /tools/ address from 29 March 2024. | seo.ai/privacy-policy |
| Independent studies | 1 record | Studies index |
The page names five generators: "Detect AI-generated content from ChatGPT, GPT-4, Bard, Claude, and Gemini in any language with our Free AI Detector Tool. Utilizing four advanced AI-detection models powered by cutting-edge algorithms, our tool delivers an impressive 98.4% (accuracy rate)" (seo.ai/tools/ai-content-detector, read 10 November 2026). The card counts four under the index rule that takes the GPT family once: GPT, Bard, Claude and Gemini. The result is a probability: "A score of 1% indicates human-made content, while a score nearing 100% suggests a high probability of being AI-generated." The widget that runs the check returns four sub-scores it labels Prediction, Entropy, Perplexity and Diversity, while the FAQ beneath it explains "Prediction, Entropy, Correlation and Perplexity", a mismatch the card records as it stands (tools.seo.ai/build/AiContentDetector.js, read 10 November 2026).
Language is the page's widest claim. "Detect AI Content written in 50+ languages," it says, and lists 46 by name from Arabic and Basque to Ukrainian and Vietnamese before closing with "...and more!" (read 10 November 2026). The card records 50, the vendor's stated figure, and the named list, and SEO.ai enters the languages ranking on that count. No study in the index has tested the tool in any language but English. The nearest cards are Writer, whose 14% false positive rate in Walters 2023 sits one place above SEO.ai's, and Sapling, which returned "uncertain" on 31% of the same 42 human papers in Walters 2023, the next-largest share after SEO.ai's 55% (DOI 10.1515/opis-2022-0158, Table 4, read 8 November 2026).
Limits and plans
| Plan | Price | Limits | Checked on |
|---|---|---|---|
| AI Content Detector (free tool) | Free | No login; 20,000 characters per check (widget); AI probability score with four sub-scores (read 10 November 2026). | |
| Single Site (SEO platform) | $149 per month | For one website in one language: AI agent, content recommendations and publishing plan, backlinks, Google Ads, monitoring, human support; the detector is not listed as a plan feature (pricing page, Pricing-Jul-2025, read 10 November 2026). | |
| Multi Site (SEO platform) | $299 per month | Up to 3 websites or languages, with 5, 10 and more than 10 selectable; the same features as the single website plan (read 10 November 2026). |
Input is paste only and needs no login, which the page title states as "Free AI Content Detector, Super Fast, No Login Required" (seo.ai/tools/ai-content-detector, read 10 November 2026). The page's description says "Check up to 25.000 characters of text with SEO.ai Content Detector", but the widget enforces a smaller figure: its counter reads "N characters (Max 20000 allowed)" and the code cuts the input at 20,000 characters (tools.seo.ai/build/AiContentDetector.js, read 10 November 2026). The card records 20,000, the enforced limit, about 3,600 words at 5.5 characters a word, and notes the 25,000 as a contradiction. The widget posts to tools.seo.ai/api/ai-detection, an endpoint with no documentation page, so the card records no API. No file upload, no minimum, no daily figure and no monthly allowance is stated, and SEO.ai sits in the second table of the free tiers ranking.
The pricing page sells the SEO platform, not the detector, which it lists under "Free Tools (Popular)" in the footer (seo.ai/pricing, Pricing-Jul-2025, read 10 November 2026). The rows are recorded as displayed because they are the only prices on the site.
Retention is stated for personal data only. The Privacy Policy reads: "We retain personal information only as long as necessary to fulfill the purposes described above and comply with applicable legal obligations. Upon expiration of these purposes or at your request, information is securely deleted" (seo.ai/privacy-policy, Effective April 10th, 2025, Version 1.3, read 10 November 2026). The policy lists names, business emails, company and payment details and data from Google integrations, and says nothing about text pasted into the free tools; the Terms define "User Content" as "texts, files, links, images, photos, audio, mixed media content" submitted to the platform and choose Danish law with the District Court in Copenhagen as venue (seo.ai/terms, sections 5.2.1 and 18.1, read 10 November 2026). No period is stated, so the retention rank field is empty and the clause is quoted in the unranked table of the data retention ranking.
What the vendor claims
Detector page (read 10 November 2026): Utilizing four advanced AI-detection models powered by cutting-edge algorithms, our tool delivers an impressive 98.4% (accuracy rate), all thanks to our state-of-the-art algorithm. The capture of 3 October 2023 printed It employs four distinct AI-detection models, delivering 98.4% (accuracy). No dataset, date or method is published. The FAQ on the same page: AI detectors aren't highly accurate because advanced LLMs produce content that's nearly indistinguishable from human writing.
SEO.ai states one figure and has stated it since 2023. The live page reads "our tool delivers an impressive 98.4% (accuracy rate), all thanks to our state-of-the-art algorithm", and the Wayback capture of 3 October 2023 printed "It employs four distinct AI-detection models, delivering 98.4% (accuracy)" (archived page, captured 3 October 2023, read 10 November 2026). No dataset, date or method accompanies the number on either version. The FAQ on the same live page pulls the other way: "AI detectors aren't highly accurate because advanced LLMs produce content that's nearly indistinguishable from human writing. Instead of relying solely on detection, focus on making the text sound natural and authentic" (seo.ai/tools/ai-content-detector, read 10 November 2026). On false positives the FAQ says: "Yes, a false positive occurs when an AI detector incorrectly identifies human-created content as being likely generated by an AI [...] In fact, even large portions of the Bible have humorously been flagged as 'AI-generated'!" No rate is published.
The page makes no claim to catch paraphrased text and answers the opposite question. "How to avoid and get around AI Content Detection?" is a FAQ item, with the answer that "mixing human writing with AI can make text less predictable and harder to detect" (read 10 November 2026), and the site sells an AI Paraphrasing Tool and an Article Rewriter in the same free-tools list.
What independent studies found
- AIDI-S-0003Walters 20232023
SEO.ai: 72% of 126 documents correct, 4% incorrect, 24% uncertain (Table 4); 92% of 84 AI papers correct, 0 called human; 100% of 42 GPT-3.5 and 83% of 42 GPT-4 papers correct; 33% of 42 human papers correct, 12% called AI (the third-highest false positive rate of 16, after Crossplag and Writer at 14%) and 55% uncertain. Tested June 25 to July 12, 2023.
One record in the studies index tested the tool. Walters 2023 ran SEO.ai between June 25 and July 12, 2023 on 42 ChatGPT-3.5 literature reviews, 42 ChatGPT-4 literature reviews and 42 human-written first-year composition papers. Table 4 prints 72% of the 126 documents correct, 4% incorrect and 24% uncertain; on the 84 AI papers 92% correct and 0 called human; 100% of the GPT-3.5 papers and 83% of the GPT-4 papers correct; and on the 42 human papers 33% correct, 12% called AI and 55% uncertain (DOI 10.1515/opis-2022-0158, Table 4, read 8 November 2026). The paper's text names the tool in its false positive group: Crossplag and Writer at 14%, SEO.ai at 12% and Content at Scale at 10%, "while the other detectors each have no more than a single false positive within the set of 42 human-generated documents."
The fields follow the index rules. The false positive value is 12% of 42, because the study record prints that figure for SEO.ai by name. The false negative value stays empty: Table 4 prints 0 of 84 AI papers called human, but the record prints no per-tool false negative for SEO.ai, and the rule for this wave takes a Walters value only where the record prints one; the data file notes the Table 4 figure for the merge. The claim gap pairs the page's 98.4% with the 72% overall share, a gap of 26.4 points, the index's treatment of a mixed-set accuracy; paired with the 92% share on the AI papers alone the gap would be 6.4 points, and the data file records both. Read together, the Walters figures describe a tool that caught almost every AI paper it was shown and would not commit on more than half of the human ones.
Where SEO.ai appears in the index
Rankings
- AIDI-R-01AI detectors ranked by independent testing Two records added in the fifth wave on 9 November 2026, Pegoraro 2023 and Fleckenstein 2024, changed nine counts and none: Pegoraro 2023 tested ZeroGPT, GPTZero, Copyleaks, Originality.ai, Writer, Content at Scale (BrandWell), DetectGPT, the GPT-2 Output Detector and GLTR, lifting GPTZero to 12, the GPT-2 Output Detector to 10, Copyleaks to 7 and Originality.ai and ZeroGPT to 6; Fleckenstein 2024 tested 289 teachers and no software, so it counts for no card ([Fleckenstein 2024 record](/studies/fleckenstein-2024-teachers/)). Illuminarty, one of four cards added in the same wave, joined with its one image record from Ha and Passananti 2024, so 18 of 72 cards now qualify.
- AIDI-R-02AI detector false positive rates, ranked
- AIDI-R-04AI detectors ranked by languages supported
- AIDI-R-05AI detectors ranked by maximum input per check
- AIDI-R-10AI detector accuracy claims vs published results, ranked by the gap
- AIDI-R-17AI detectors ranked by the generator models the vendor names
Fits these use cases
- Not listed in a use-case view at this index version.
SEO.ai ranks on one study record in independently tested detectors, at 12% in the false positive ranking, at 26.4 points in the claim versus evidence gap, at 50 in languages, at four in generator models named and at 20,000 characters in the input limits ranking, each read in the data file on 10 November 2026. It qualifies for the no-account view on its page title and appears in the GPT-4 question at 83% of 42 GPT-4 papers. It does not appear in the free tier, retention, API or false negative rankings, because the vendor states no allowance, no period and no API, and the record names no false negative figure for it.
Every detector card on the register shows SEO.ai with the same fields as the detectors that publish a false positive rate of their own, so a reader can set the 98.4% on the page against the 12% of human papers the one study saw it flag.
Questions about the SEO.ai AI Content Detector
How accurate is the SEO.ai AI Content Detector?
72% of 126 documents correct in Walters 2023 (Table 4), with 4% incorrect and 24% uncertain; 100% on ChatGPT-3.5 papers and 83% on ChatGPT-4 papers, read in the primary paper on 8 November 2026. The vendor's page claims 98.4% with no dataset or date, read 10 November 2026.
What is SEO.ai's false positive rate?
12% of 42 human-written papers called AI in Walters 2023 (Table 4), with 55% of them returned uncertain, the third-highest rate of 16 detectors after Crossplag and Writer at 14%, read 8 November 2026. The vendor publishes no rate.
Is the SEO.ai AI detector free?
Yes. The page title reads "Free AI Content Detector, Super Fast, No Login Required", and the widget takes 20,000 characters per check with no stated quota, read 10 November 2026. The $149 and $299 monthly plans price the SEO platform, not the detector.
How much text can SEO.ai check at once?
20,000 characters, the maximum the widget's counter and code enforce ("Max 20000 allowed"), read 10 November 2026; the page's description says 25,000, a figure the widget does not allow.
Which languages does SEO.ai say it detects?
"50+ languages", with 46 named on the page from Arabic to Vietnamese, read 10 November 2026; no indexed study has tested the tool outside English.
Who operates SEO.ai?
Ninety ApS, Diplomvej 381, 2800 Kongens Lyngby, Denmark, business registration DK43096990, under Danish law with the District Court in Copenhagen as venue, per the privacy policy and terms read 10 November 2026.
Sources and revisions
Sources
- seo.ai/tools/ai-content-detectorRead 10 November 2026
- tools.seo.ai/build/AiContentDetector.jsRead 10 November 2026
- web.archive.org/web/20231003175329/https:...Read 10 November 2026
- seo.ai/pricingRead 10 November 2026
- seo.ai/privacy-policyRead 10 November 2026
- seo.ai/termsRead 10 November 2026
- degruyterbrill.com/document/doi/10.1515/o...Read 8 November 2026
). Illuminarty, one of four cards added in the same wave, joined with its one image record from Ha and Passananti 2024, so 18 of 72 cards now qualify.: register plate](/img/independently-tested-480.webp)
