{"id":25987,"date":"2026-06-19T15:49:00","date_gmt":"2026-06-19T15:49:00","guid":{"rendered":"https:\/\/undetectable.ai/blog\/?p=25987"},"modified":"2026-09-08T14:43:11","modified_gmt":"2026-09-08T14:43:11","slug":"what-ai-detector-do-teachers-use","status":"publish","type":"post","link":"https:\/\/undetectable.ai/blog\/what-ai-detector-do-teachers-use\/","title":{"rendered":"What AI Detector Do Teachers Use? A Complete Guide"},"content":{"rendered":"<p>If you\u2019re wondering <em>what AI detector do teachers use<\/em>, the answer is actually pretty boring: whatever the school pays for.<\/p>\n<p>And for most universities and K-12 districts across the United States, that\u2019s Turnitin.<\/p>\n<p>But after spending years studying AI detectors and running Undetectable AI, I\u2019ve realized that the good teachers don\u2019t stop there. They\u2019ll often use <em>another<\/em> detector for a second opinion.<\/p>\n<p>So if you\u2019re a teacher looking for a reliable backup AI detector, or maybe you\u2019re a student curious about what your teacher might be using behind the scenes, this guide is for you.<\/p>\n<p>I\u2019m comparing four popular second-opinion AI detectors based on accuracy, compliance, pricing, and how useful they are for teachers.<\/p>\n<p>I\u2019m also sharing some key research on why no AI detector score should ever be treated as evidence on its own, especially when evaluating student work.<\/p>\n<hr \/>\n<p><strong>Key Takeaways<\/strong><\/p>\n<ul>\n<li>For most teachers, Turnitin is the default AI detector because it\u2019s built into their school\u2019s workflow. However, many teachers also use an additional AI detector alongside Turnitin.<\/li>\n<li>In our testing and research on what AI detectors teachers use, <a href=\"https:\/\/undetectable.ai\/\" target=\"_blank\" rel=\"noopener\">Undetectable AI\u2019s<\/a> AI Detector was the strongest second-opinion option for teachers, combining high accuracy with a generous 10,000-word free limit that lets teachers scan full essays at once.<\/li>\n<li>Even in 2026, AI detectors still struggle with certain types of writing, with a Stanford study finding that some detectors incorrectly flagged essays written by non-native English speakers as AI-generated more than half the time.<\/li>\n<li>The best teachers <em>never<\/em> rely on a single AI detector score when evaluating the authenticity of a student\u2019s work. Instead, they look for agreement across multiple AI detectors and compare the result against a student\u2019s revision history and previous work.<\/li>\n<\/ul>\n<hr \/>\n<h2>What Is an AI Detector?<\/h2>\n<p>Before we get into the top AI detectors teachers use, it\u2019s worth taking a moment to understand what an AI detector is, and what it isn\u2019t.<\/p>\n<p>Despite the name, AI detectors don\u2019t actually \u201cknow\u201d whether a student used ChatGPT or another <a href=\"https:\/\/litero.ai\/\" target=\"_blank\" rel=\"noopener\">AI writing tool<\/a>. Instead, they analyze patterns in the text and estimate how likely it is to have been generated by AI.<\/p>\n<p>Most detectors rely on statistical signals such as perplexity and burstiness.<\/p>\n<p><!-- inline-cta --><\/p>\n<p>Perplexity measures how predictable the word choices are. In general, AI-generated writing tends to be more predictable because language models often favor common words and sentence patterns, while human writing is usually less predictable and contains more variation.<\/p>\n<p>Burstiness measures how much sentence length and structure change throughout a piece of writing. Humans naturally mix short, long, simple, and complex sentences. AI writing is often more uniform.<\/p>\n<p>Based on these signals, the detector returns a probability score of how \u201clikely\u201d a piece of text is to be AI-generated or human.<\/p>\n<p>This is very different from plagiarism checkers, which compare text against existing sources, or revision-history tools, which show how a document was created over time. AI detectors don\u2019t see intent, editing history, or the writing process. They only analyze the final text that\u2019s submitted.<\/p>\n<h2>The 4 Best Second-Opinion AI Detectors for Teachers<\/h2>\n<p>When we set out to find what AI detector teachers use, we quickly realized that most teachers aren\u2019t really looking for a replacement for <a href=\"https:\/\/undetectable.ai\/blog\/can-turnitin-detect-paraphrasing\/\" target=\"_blank\" rel=\"noopener\">Turnitin<\/a>; they\u2019re just looking for a second opinion.<\/p>\n<p>With that in mind, and after reviewing dozens of tools, four names kept coming up again and again: Undetectable AI, Quillbot, Winston AI, and Scribbr.<\/p>\n<p>To put the top ones to the test, we generated a 400-word essay using ChatGPT (GPT-5.5) and submitted the exact same text to every detector.<\/p>\n<p>We also researched and evaluated each tool on a few factors that are important to teachers, including:<\/p>\n<ul>\n<li>Free usage limits and restrictions<\/li>\n<li>Pricing and paid plan availability<\/li>\n<li>Sentence-level analysis features<\/li>\n<li>LMS and classroom integrations<\/li>\n<li>Compliance and security disclosures<\/li>\n<li>Overall ease of use for educators<\/li>\n<\/ul>\n<p>Before we get into the details, strengths, and weaknesses of each platform, the following table provides a quick side-by-side comparison of all four tools.<\/p>\n<p><!-- html-block --><\/p>\n<div class=\"blog-wp-table\">\n<table class=\"has-fixed-layout\">\n<thead>\n<tr>\n<th class=\"has-text-align-center\" colspan=\"5\" data-align=\"center\"><strong>Undetectable vs Quillbot vs Winston AI vs Scribbr: Quick Facts<\/strong><\/th>\n<\/tr>\n<tr>\n<th class=\"has-text-align-center\" data-align=\"center\"><strong>Criteria<\/strong><\/th>\n<th class=\"has-text-align-center\" data-align=\"center\"><strong>Undetectable AI<\/strong><\/th>\n<th class=\"has-text-align-center\" data-align=\"center\"><strong>Quillbot<\/strong><\/th>\n<th class=\"has-text-align-center\" data-align=\"center\"><strong>Winston AI<\/strong><\/th>\n<th class=\"has-text-align-center\" data-align=\"center\"><strong>Scribbr<\/strong><\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Accuracy<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Very Accurate<br \/>\nFlagged our 100% AI-generated essay as 99% likely AI<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Very Accurate<br \/>\nFlagged our 100% AI-generated essay as 100% likely AI<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Very Accurate<br \/>\nFlagged our 100% AI-generated essay as 100% likely AI<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Very Accurate<br \/>\nFlagged our 100% AI-generated essay as 0% human<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Free tier word limit<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">10,000 words per scan<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">1,200 words per scan<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">2,000 characters per scan<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">1,200 words per scan<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Paid pricing<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Plans range from $5 per month to $42 per month.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Plans range from $8.33 per month to $19.95 per month.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Plans range from $10 per month to $26 per month.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">$8.33 per month, billed annually for unlimited AI detection.<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>FERPA-Compliant<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>SOC 2-Compliant<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes.<br \/>\nSource: Winston AI privacy matters<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>AICPA-Compliant<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Not publicly stated.<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Learning Management System (LMS) Integrations<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">API access supported, no specific LMS integrations listed.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">No LMS integrations listed.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes, Google Classroom.<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">No LMS integrations listed.<\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Sentence-Level Highlighting<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Yes<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><!-- \/html-block --><\/p>\n<h3>Undetectable AI Detector<\/h3>\n<p>When I put myself in a teacher\u2019s shoes, I realized that our own Undetectable AI Detector is one of the few tools that allows you to check an entire essay without immediately running into a word limit.<\/p>\n<p>The free version supports up to 10,000 words per scan, which is significantly more generous than others on this list. That makes it practical for reviewing longer assignments without splitting text into multiple submissions.<\/p>\n<p>In terms of accuracy, Undetectable AI correctly identified the AI-generated essay as 99% AI. Beyond the score itself, the tool also provides sentence-level highlighting, making it easier to see which sections of a paper are triggering the detection result.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-undetectable-ai-correctly-identified-the-ai-generated-essay-as-99-.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-undetectable-ai-correctly-identified-the-ai-generated-essay-as-99-.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-undetectable-ai-correctly-identified-the-ai-generated-essay-as-99-.webp\" class=\" sp-no-webp\" alt=\"\" decoding=\"async\"  > <\/picture><\/p>\n<p>I\u2019d also like to note here that because our AI Detector is built by the team behind our <a href=\"https:\/\/undetectable.ai\/blog\/what-is-the-best-ai-humanizer\/\" target=\"_blank\" rel=\"noopener\">AI Humanizer<\/a>, it has visibility into how AI-generated text is commonly edited and rewritten before submission.<\/p>\n<p>This is super useful in educational settings, where students rarely submit raw ChatGPT output without making changes.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-privacy-policy-1024x562-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-privacy-policy-1024x562-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-privacy-policy-1024x562-1.webp\" class=\" sp-no-webp\" alt=\"\" decoding=\"async\"  > <\/picture><\/p>\n<p>In terms of privacy and compliance, we don\u2019t currently publish FERPA, SOC 2, or AICPA compliance certifications on our website. For individual educators using Undetectable AI as a secondary checker, this isn\u2019t usually a major concern.<\/p>\n<p>However, if this is a priority for your school, please feel free to get in touch, and we\u2019d be happy to discuss our privacy practices and answer any questions.<\/p>\n<p>Overall, here\u2019s what teachers tend to like the most about Undetectable AI, and where it falls short.<\/p>\n<p><!-- html-block --><\/p>\n<div class=\"blog-wp-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td class=\"has-text-align-center\" colspan=\"2\" data-align=\"center\"><strong>Undetectable AI: Pros and Cons at a Glance<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>What Teachers Like<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Where it Falls Short<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\">Generous free limits (10,000 words)Fast scansClear sentence-level highlighting<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Like every detector, it can occasionally misclassify human writing.Larger schools and districts may require additional compliance documentation before adoption.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><!-- \/html-block --><\/p>\n<h3>Quillbot AI Detector<\/h3>\n<p>QuillBot AI Detector is one of the easiest AI detectors to try. It\u2019s free to use, doesn\u2019t require an account, and is part of the broader Quillbot writing suite that many students already use for paraphrasing and grammar assistance.<\/p>\n<p>In our test, Quillbot correctly identified the AI-generated essay as AI-written, making it a decent quick-check tool. However, its lower scan limits and history of false positives make it better suited as a lightweight secondary check rather than a tool teachers should rely on heavily.<\/p>\n<p>For teachers looking for a quick second opinion, that\u2019s good news.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-if-quillbot-premium-e1782931552712-1024x299-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-if-quillbot-premium-e1782931552712-1024x299-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-if-quillbot-premium-e1782931552712-1024x299-1.jpg\" class=\" sp-no-webp\" alt=\"Screenshot of Quillbot premium\" decoding=\"async\"  > <\/picture><\/p>\n<p>That said, Quillbot is best viewed as a supplementary tool rather than a primary decision-maker. While it performs well on straightforward AI-generated content, there have been documented cases where it produced high AI scores on text written before ChatGPT existed.<\/p>\n<p>This highlights a challenge shared by many AI detectors: predictable human writing can sometimes resemble AI-generated text.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-trust-page-e1782931569320-1024x448-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-trust-page-e1782931569320-1024x448-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-trust-page-e1782931569320-1024x448-1.jpg\" class=\" sp-no-webp\" alt=\"Screenshot of Trust page\" decoding=\"async\"  > <\/picture><\/p>\n<p>From a compliance perspective, Quillbot does not publicly advertise FERPA compliance, SOC 2 certification, or other education-specific compliance standards. Schools with strict privacy requirements may want to review institutional policies before using the platform with student work.<\/p>\n<p>All in all, here\u2019s what teachers tend to like the most (and the least) about Quillbot.<\/p>\n<p><!-- html-block --><\/p>\n<div class=\"blog-wp-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td class=\"has-text-align-center\" colspan=\"2\" data-align=\"center\"><strong>Quillbot AI Detector: Pros and Cons at a Glance<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>What Teachers Like<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Where It Falls Short<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\">Free to use with no signup required\u00a0Simple interface with virtually no learning curveUseful for a quick second opinion on shorter assignments<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Can produce false positives on highly structured human writingFERPA and SOC 2 compliance certifications are not publicly disclosed. Some users report stability issues with browser and Word integrationsMuch lower per scan word limit compared to Undetectable AI<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><!-- \/html-block --><\/p>\n<h3>Winston AI<\/h3>\n<p>Winston AI is the most education-focused detector we tested. In addition to AI detection, it also offers OCR for scanned handwriting and PDF submissions, plus Google Classroom integration for teachers who want AI detection built into their existing workflow.<\/p>\n<p>In our test, Winston AI correctly identified the AI-generated essay as AI-written, returning a score of 0% human. It was one of the strongest performers overall and stands out for features designed specifically for educators rather than general consumers.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-score-1024x430-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-score-1024x430-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-score-1024x430-1.webp\" class=\" sp-no-webp\" alt=\"\" decoding=\"async\"  > <\/picture><\/p>\n<p>Winston AI stands out for institutions that prioritize formal security documentation, but for most individual teachers, those enterprise-level requirements may not outweigh practical considerations like scan limits, speed, and accessibility.<\/p>\n<p>It is the only detector in this comparison that publicly states SOC 2 compliance, making it a stronger fit for schools and districts with formal privacy and procurement requirements.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-privacy-policy-e1782931510715-1024x460-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-privacy-policy-e1782931510715-1024x460-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-privacy-policy-e1782931510715-1024x460-1.jpg\" class=\" sp-no-webp\" alt=\"Screenshot of Winston AI privacy policy\" decoding=\"async\"  > <\/picture><\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-faqs-1024x377-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-faqs-1024x377-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-winston-ai-faqs-1024x377-1.webp\" class=\" sp-no-webp\" alt=\"\" decoding=\"async\"  > <\/picture><\/p>\n<p>While Winston does not publicly advertise FERPA certification, its transparency around security practices is stronger than many competing AI detectors.<\/p>\n<p>The trade-off is accessibility. Winston\u2019s free tier is significantly more restrictive than Undetectable AI\u2019s, and its interface can feel more feature-heavy if you\u2019re simply looking for a quick second opinion on a paper.<\/p>\n<p>Here\u2019s a quick look at Winston\u2019s pros and cons at a glance.<\/p>\n<p><!-- html-block --><\/p>\n<div class=\"blog-wp-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td class=\"has-text-align-center\" colspan=\"2\" data-align=\"center\"><strong>Winston AI: Pros and Cons at a Glance<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>What Teachers Like<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Where It Falls Short<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\">Google Classroom integration OCR support for handwritten assignments and PDFs Publicly disclosed SOC 2 complianceStrong fit for institutional workflows<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">Some users report a high amount of <a href=\"https:\/\/www.g2.com\/products\/winston-ai\/reviews\" target=\"_blank\" rel=\"nofollow noopener\">false positives on shorter passages<\/a> Restrictive free tier Much lower per scan word limit compared to Undetectable AI<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><!-- \/html-block --><\/p>\n<h3>Scribbr AI Detector<\/h3>\n<p>Scribbr is one of the most recognizable brands in academic writing. Many teachers and students already know it for citation generators, plagiarism checking, proofreading services, and other educational tools, which makes its AI detector a natural place to start.<\/p>\n<p>In our test, Scribbr correctly identified the AI-generated essay as AI-written, which is a great start.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-ai-detector-score-1024x589-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-ai-detector-score-1024x589-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-ai-detector-score-1024x589-1.webp\" class=\" sp-no-webp\" alt=\"\" decoding=\"async\"  > <\/picture><\/p>\n<p>However, Scribbr also notes that its free detector is less accurate than the premium version. That distinction matters because a clean score on the free tier doesn\u2019t necessarily mean you\u2019re seeing the full capabilities of the platform\u2019s detection engine.<\/p>\n<p>For educators who already use Scribbr\u2019s academic tools, its AI detector can be a convenient secondary option. However, its lower free limits and premium-gated accuracy make it less flexible for frequent classroom use.<\/p>\n<p>However, teachers should keep in mind that the most advanced detection features sit behind a paywall.<\/p>\n<p>From a compliance standpoint, Scribbr does not publicly advertise FERPA, SOC 2, or AICPA compliance certifications. As a result, it\u2019s generally better suited for individual checks than institution-wide academic integrity workflows.<\/p>\n<p><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-privacy-page-e1782931530735-1024x683-1.avif \"  type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-privacy-page-e1782931530735-1024x683-1.webp \"  type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2026\/08\/screenshot-of-scribbr-privacy-page-e1782931530735-1024x683-1.jpg\" class=\" sp-no-webp\" alt=\"Screenshot of Scribbr Privacy page\" decoding=\"async\"  > <\/picture><\/p>\n<p>Like every detector we tested, Scribbr has clear strengths and a few notable weaknesses. Here\u2019s the short version.<\/p>\n<p><!-- html-block --><\/p>\n<div class=\"blog-wp-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td class=\"has-text-align-center\" colspan=\"2\" data-align=\"center\"><strong>Scribbr AI Detector: Pros and Cons at a Glance<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>What Teachers Like<\/strong><\/td>\n<td class=\"has-text-align-center\" data-align=\"center\"><strong>Where It Falls Short<\/strong><\/td>\n<\/tr>\n<tr>\n<td class=\"has-text-align-center\" data-align=\"center\">Familiar and trusted academic brandClean, ad-free interfacePart of a broader academic writing ecosystem<\/td>\n<td class=\"has-text-align-center\" data-align=\"center\">The free detector is less accurate than the premium versionFERPA, SOC 2, and AICPA compliance certifications are not publicly disclosedLike all AI detectors, <a href=\"https:\/\/www.reddit.com\/r\/CollegeRant\/comments\/1e8xme7\/received_a_zero_because_my_essay_was_flagged_as\/\" target=\"_blank\" rel=\"nofollow noopener\">false positives<\/a> are an issueMuch lower per scan word limit compared to Undetectable AI<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><!-- \/html-block --><\/p>\n<h2>Independent Studies on Detector Accuracy<\/h2>\n<p>Before trusting any AI detector score, it\u2019s worth looking at what independent research says about these tools.<\/p>\n<p>One of the biggest challenges in AI detection is that accuracy isn\u2019t consistent across every type of writing. A detector might perform well on a clearly AI-generated essay but struggle with edited content, mixed human-AI writing, or work written by non-native English speakers.<\/p>\n<p>That\u2019s why most researchers recommend treating AI detector scores as one signal among many, not definitive evidence that a student used AI.<\/p>\n<p>Here are two of the most widely cited studies on the topic.<\/p>\n<h3>Stanford 2023: Bias Against Non-Native English Writers<\/h3>\n<p>One of the most influential studies on AI detection came from researchers at <a href=\"https:\/\/arxiv.org\/pdf\/2304.02819\" target=\"_blank\" rel=\"noopener\">Stanford University in 2023<\/a>.<\/p>\n<p>Researchers found that several popular AI detectors incorrectly flagged TOEFL essays written by non-native English speakers as AI-generated at alarmingly high rates.<\/p>\n<p>Even though the detectors achieved near-perfect accuracy on essays written by U.S. eighth-grade students, they falsely classified 61.22% of TOEFL essays as AI-generated.<\/p>\n<p>At Undetectable AI, we know that false positives can be incredibly frustrating for both students and educators. We also know, based on Stanford\u2019s research, that this is an industry-wide issue, <em>not<\/em> an issue with a handful of AI detectors.<\/p>\n<p>That\u2019s why AI detector scores should <em>never<\/em> be treated as standalone evidence of AI use or academic misconduct.<\/p>\n<h3>Turnitin\u2019s Own ELL Bias Study<\/h3>\n<p>In response to concerns about bias against non-native English writers, Turnitin conducted its own study on English Language Learner (ELL) writing samples.<\/p>\n<p>The company reported a false-positive rate of just 0.014% for submissions that met its 300-word minimum requirement, concluding that its AI detector showed no statistically significant bias against ELL writers.<\/p>\n<p>That\u2019s a dramatically different result from Stanford\u2019s findings. However, it\u2019s important to remember that Turnitin\u2019s research was conducted and published by Turnitin itself rather than by an independent academic research group. And like any self-sponsored research, it should be taken with a grain of salt.<\/p>\n<p>For teachers, the primary takeaway isn\u2019t that one study is \u201cright,\u201d and the other is \u201cwrong\u201d. It\u2019s that AI detection remains an evolving field, and detector scores should always be interpreted alongside other evidence.<\/p>\n<h2>Why Undetectable AI Is the Best Choice for Teachers<\/h2>\n<p>After testing all four tools, one thing became clear: while several AI detectors can identify obvious AI-generated writing, Undetectable AI offers the most practical and teacher-friendly experience overall.<\/p>\n<p>Unlike many detectors that limit scans to short passages, Undetectable AI allows up to 10,000 words per check, making it far more useful for reviewing full essays, research papers, and long-form assignments without splitting content into multiple scans.<\/p>\n<p>It also combines AI detection with sentence-level analysis, plagiarism checking, citation tools, paraphrasing support, and browser integrations, giving teachers a more complete academic integrity toolkit instead of a standalone detector.<\/p>\n<p>For educators using Google Docs, our Chrome extension makes it easy to scan writing directly inside the browser, which creates a smoother workflow similar to classroom tools like Google Classroom integrations.<\/p>\n<p>While tools like Quillbot, Winston AI, and Scribbr can provide useful second opinions, they each come with trade-offs in word limits, accessibility, or workflow flexibility.<\/p>\n<p>For teachers who want speed, flexibility, and deeper analysis in one place, Undetectable AI remains the strongest second-opinion detector available today.<\/p>\n<h2>When AI Detectors Get It Wrong<\/h2>\n<p>One of the biggest misconceptions about AI detectors is that they look for \u201cproof\u201d of AI use.<\/p>\n<p>They don\u2019t.<\/p>\n<p>AI detectors are <em>statistical<\/em> tools, which means they make predictions based on <em>patterns<\/em> in the text. And like any prediction system, they have predictable failure modes.<\/p>\n<p>The best-documented example is writing from non-native English speakers.<\/p>\n<p>As we saw in the Stanford study, several leading AI detectors incorrectly flagged TOEFL essays as AI-generated at surprisingly high rates.<\/p>\n<p>Turnitin\u2019s own research reached different conclusions, but both studies point to the same reality: evaluating English Language Learner (ELL) writing remains one of the biggest challenges in AI detection.<\/p>\n<p>Formulaic human writing can also trigger false positives.<\/p>\n<p>Academic essays, standardized test responses, and highly structured assignments often follow predictable patterns.<\/p>\n<p>In <a href=\"https:\/\/anangsha.substack.com\/p\/i-tested-30-ai-detectors-here-are\" target=\"_blank\" rel=\"noopener\">one example<\/a>, Quillbot reportedly flagged text written before ChatGPT even existed as 87% AI-generated. This highlights an important limitation of <em>all<\/em> AI detection tools: predictable writing doesn\u2019t necessarily mean AI was involved.<\/p>\n<p>Short submissions create another challenge.<\/p>\n<p>Most detectors become less reliable when evaluating text under 150 to 300 words because there simply isn\u2019t enough content to measure patterns like perplexity and burstiness with confidence. That\u2019s one reason many AI detection providers recommend minimum word counts before interpreting results.<\/p>\n<p>All of these examples lead me to my final point: no detector score is evidence of AI-use on its own. But it <em>is<\/em> a reason to have a conversation and dig deeper.<\/p>\n<h2>What Teachers Should Do Before Accusing a Student<\/h2>\n<p>So you\u2019ve got a paper that scored highly on an AI detector. What now?<\/p>\n<p>Before raising an academic integrity concern, it\u2019s worth taking a few extra steps to make sure you\u2019re seeing the full picture.<\/p>\n<p>For example, you can:<\/p>\n<ul>\n<li><strong>Verify the result with a second detector.<\/strong> Never rely on a single AI detector score. If one tool flags a paper, run it through at least one other detector and see if it flags similar passages.<\/li>\n<li><strong>Review the document\u2019s revision history.<\/strong> In Google Docs or Microsoft Word, AI-generated content that\u2019s been pasted in often appears as one large insertion. Human writing typically shows a more gradual pattern of drafting, editing, and revision.<\/li>\n<li><strong>Compare the paper to the student\u2019s previous work.<\/strong> This is often the most reliable signal of all. Look for sudden changes in vocabulary, sentence structure, writing quality, or argumentation style.<\/li>\n<li><strong>Look for context, not just scores.<\/strong> Consider classroom performance, participation, rough drafts, outlines, and other evidence that helps explain how the assignment was completed.<\/li>\n<li><strong>Start a conversation before making an accusation.<\/strong> Instead of leading with the detector score, ask the student to walk you through their writing process. Genuine questions will always reveal more about a student than any AI detector can.<\/li>\n<li><strong>Consider alternative resolutions.<\/strong> If concerns remain, a revision assignment, oral defense, or follow-up writing exercise is usually more defensible than relying on detector scores alone.<\/li>\n<\/ul>\n<p>In short, no AI detector should be the sole basis for an accusation, and every flagged paper deserves additional review before any action is taken.<\/p>\n<h2>Frequently Asked Questions About What AI Detectors Teachers Use<\/h2>\n<h3>What is the best AI detector for teachers?<\/h3>\n<p>For most teachers, the best AI detector is used alongside . Turnitin remains the institutional default in many schools, but Undetectable AI combines <a href=\"https:\/\/undetectable.ai\/blog\/does-undetectable-ai-work\/\" target=\"_blank\" rel=\"noopener\">high accuracy<\/a>, larger scan limits, and detailed sentence-level analysis, making it a more flexible option for reviewing full student submissions.<\/p>\n<h3>Do teachers actually use AI detectors?<\/h3>\n<p>Yes. Most colleges, universities, and many K-12 districts now have access to AI detection through Turnitin. Many teachers also use free tools like Undetectable AI, Quillbot, Winston AI, or Scribbr when they want a second opinion or additional context.<\/p>\n<h3>What\u2019s the best free AI detector for teachers?<\/h3>\n<p>Undetectable AI offers one of the largest free scan limits among major AI detectors, allowing up to 10,000 words per scan. This allows you to check full essays without hitting paywalls or character limits.<\/p>\n<h3>Is Quillbot AI Detector reliable for grading?<\/h3>\n<p>No AI detector is 100% reliable for grading on its own. Quillbot is useful for a quick check, but it has documented cases of flagging pre-2022 human text as AI.<\/p>\n<p>No matter what AI detector you use, you should <em>always<\/em> pair it with another detector and take time to review other signals too, like the student\u2019s revision history, previous writing samples, and overall classroom performance.<\/p>\n<h3>Can teachers tell if I used ChatGPT?<\/h3>\n<p>Teachers look for a combination of signals, including AI detector scores, sudden changes in your writing voice, use of vocabulary you don\u2019t normally use, and a lack of revision history in Google Docs.<\/p>\n<p>A detector score alone isn\u2019t proof, but tell-tale signs like a dramatic shift in writing style or unusual vocabulary can be difficult to overlook.<\/p>\n<h3>Why do AI detectors flag human writing as AI?<\/h3>\n<p>Detectors look for predictable word choices and uniform sentence lengths. If a human writes in a highly formulaic, structured way (which is common for non-native English speakers or students following strict essay templates), the detector may misinterpret it as AI-generated text.<\/p>\n<h2>An AI Detector Score Should <em>Never<\/em> Be the Final Word<\/h2>\n<p>For most teachers, Turnitin\u2019s built-in AI detector works best when paired with a secondary tool to validate the initial results before investigating further.<\/p>\n<p>Based on our testing, Undetectable AI delivered the best balance of accuracy, usability, and flexibility for teachers.<\/p>\n<p>Its ability to scan up to 10,000 words at once, highlight suspicious passages at the sentence level, and work across multiple writing workflows makes it the most practical AI detector for educators who want a reliable second opinion.<\/p>\n<p>While no AI detector should ever be treated as final proof, <a href=\"https:\/\/undetectable.ai\/\" target=\"_blank\" rel=\"noopener\">Undetectable AI<\/a> gives teachers the strongest starting point for identifying potential AI-assisted writing while reducing unnecessary friction in the review process.<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":15,"featured_media":29520,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_themeisle_gutenberg_block_has_review":false,"footnotes":""},"categories":[31],"tags":[],"class_list":["post-25987","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-helpful-ai-content-tips"],"_links":{"self":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/25987","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/comments?post=25987"}],"version-history":[{"count":19,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/25987\/revisions"}],"predecessor-version":[{"id":32122,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/25987\/revisions\/32122"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/media\/29520"}],"wp:attachment":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/media?parent=25987"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/categories?post=25987"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/tags?post=25987"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}