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A List of 8 Best AI Detectors to Scan Your Writing
A List of 8 Best AI Detectors to Scan Your Writing
Looking for an AI detector you can rely on? Check out our list of the top 8 AI detection tools and see how they compare in accuracy, pricing, and features.
May 26, 2025
Writing with AI
10 min read
It’s late at night. The clock is moving faster than you’d like. You open up ChatGPT to type in a quick prompt, and you have a page of polished sentences in seconds. That feels like a lifesaver, for sure. And you’re not alone in that feeling, either: According to recent data, 86% of students use AI in their studies, with 24% admitting they let tools like ChatGPT handle the first draft.
That convenience comes with tension, though. Professors want proof that your words are your own, so they roll out detection systems. Students keep asking the same thing: what is the best AI detector to trust?
This article breaks down eight of the best AI detectors, including StudyAgent, that actually help you scan your writing with confidence. You’ll see which options are reliable and which best free AI detectors deserve a spot in your academic toolkit. By the end, you’ll know exactly where to turn the next time originality matters most.
Why AI Detectors Matter in Education
AI writing tools are now an almost inseparable part of student life. They save time because they can generate drafts in minutes. But sometimes, blur the line between assistance and authorship.
That’s why many educators keep asking: can professors detect ChatGPT in assignments turned in for credit? The answer depends on the strength of the detection tools they have. AI detectors make that possible, giving both sides a way to confirm originality without guesswork.
Why they matter:
- They allow professors to verify that essays meet academic standards instead of relying on suspicion.
- Students can run their own checks before submitting work, reducing the risk of unintentional plagiarism.
- Detectors provide evidence-based insights, cutting down arguments about originality or authorship.
- They encourage students to use AI responsibly by showing clear boundaries between assistance and overreliance.
What Makes a Reliable AI Detector
Not all detection platforms work the same way. Some flag too much, others miss obvious signals, and a few leave students confused about what the results actually mean.
For tools to be useful in real classrooms, they need specific qualities. The best ones balance accuracy with clarity, helping students and teachers see where issues lie. By looking at plagiarism examples alongside original writing, some of the top AI detection tools for students show exactly how reliable they are.
Feature | Why It Matters |
|---|---|
High accuracy | Detects AI-generated text with precision, reducing second-guessing. |
Low false positives | Protects genuine human writing from being mistakenly flagged as artificial. |
Results breakdown | Delivers section-by-section analysis so you know exactly where issues appear. |
Transparency | Explains how results are formed, building trust in the detection process itself. |
Versatility | Works across essays, reports, and mixed content. |
8 Best AI Detectors to Consider in 2025
So, what is the best AI detector? Well, that depends on your priorities as a user. Here’s your snapshot of our eight contenders:
Tool | Is best.. |
|---|---|
StudyAgent | for powerful and completely free AI detection |
QuillBot | for multi-language support |
Grammarly AI detector | for user-friendly interface |
Turnitin | for educators and institutions |
Smodin | for hassle-free file upload |
Originality AI | for website owners, marketers, and publishers |
Winston AI | for feature-packed subscription |
Undetectable AI | for cross-tool AI probability score |
Wonder, “How do AI detectors work?” In a nutshell, they break the text down into chunks and look for patterns in the sentence structure and word choice typically used by AI models.
StudyAgent AI Detector
Pricing: Free beta version, with affordable paid tiers for deeper scans
Target audience: Students who want precise AI detection within the same document. Educators checking for originality
Key features:
- Several AI detectors built into one platform for stronger accuracy
- Low false positives backed by tested reliability
- Paragraph-level analysis that shows exactly which parts lean AI-generated
- Algorithms updated frequently to track the newest AI writing patterns
- No restrictions on the free version during beta
StudyAgent sets itself apart by focusing on accuracy and clarity. Instead of leaving students with a percentage they don’t know how to interpret, it breaks down detection results section by section.
That makes it easier to revise only the parts flagged, keeping the rest of the paper intact. It’s one of the best AI detector platforms for anyone who needs clear, actionable insights instead of guesswork.
Here’s how StudyAgent fared in our testing:
- AI-generated content: Detected subtle phrasing from ChatGPT and other AI models with strong consistency.
- Human-written content: Handled essays and research notes without producing false positives.
- Mixed content: Successfully identified which paragraphs leaned on AI and which were original, giving a detailed map of the text.
Verdict: StudyAgent’s real strength is precision. With multiple detection engines and evolving algorithms, it’s a tool students can trust when originality matters most.
QuillBot’s AI Detector
Pricing: $8.33/month (billed annually); free plan available
Target audience: Students and researchers
Key features:
- AI content detection for multi-language texts (English, French, Spanish, German, Dutch)
- Free version limit of 1,200 words per check
- Separate scores for AI-generated, AI-generated & AI-refined, human-written & AI-refined, and human-written content
- Sentence-by-sentence AI score breakdown
QuillBot is another platform that positions itself as an all-in-one AI toolkit for students. You’ll find its AI content detector side by side with a plagiarism checker, AI humanizer, and paraphrasing tool.
Here’s how QuillBot fared in our testing:
- AI-generated content: Correctly identified AI-written content from Claude, GPT-4, and Gemini, with all three samples scored as 100% AI content
- Human-written content: Identified all three samples as 0% AI-generated content
- Mixed content: Incorrectly identified all three samples as 0% AI-generated, even though they contained unedited GPT-4 output
Verdict: QuillBot is one of those AI detector tools that are suitable for simple checks of short texts. You might find it useful if your texts are in various languages or if you don’t want to create an account to run a quick check. However, don’t count on it to accurately detect a mix of human-written and AI content.
Grammarly AI Detector
Pricing: $12/month (billed annually), free checks available
Target audience: Professional content writers, educators, students, and business teams
Key features:
- Free AI content detection for texts up to 10,000 characters
- No account required for free checks
- Detailed sentence-by-sentence breakdown (premium users only)
- User-friendly interface, especially if you’re already using Grammarly
Yes, you may know Grammarly as a proofreading tool, but it also offers an AI detector. Grammarly can detect AI-generated content produced by Gemini, ChatGPT, and Gemini and returns a percentage score.
Here’s how Grammarly fared in our testing:
- AI-generated content: Failed to accurately detect 100% AI-generated content, with scores at 73% for Gemini, 56% for Claude, and solely 25% for ChatGPT texts
- Human-written content: Inaccurately flagged human-written content as partially AI-generated in one case out of three (the score was 16%)
- Mixed content: Failed to detect AI-generated content at all, tagging all three samples as fully human-written
Verdict: Thanks to its generous 10,000-character limit, Grammarly had the potential to be one of the best free AI detectors, but its accuracy leaves much to be desired.
Turnitin AI Checker
Pricing: On demand
Target audience: Educational institutions
Key features:
- AI scores below 20% not displayed to avoid false positives
- Separate scores for AI-generated content and AI-generated and AI-paraphrased text
- Sentence-by-sentence breakdown
- AI scores displayed only to educators
Turnitin, a premier originality detection software for U.S. educational institutions, launched its most accurate AI checker tool in 2023, with AI scans running by default on every paper submitted to it. The company is quite transparent about its AI checker model and has even published a whitepaper on its architecture and testing protocol. It also admits it might miss up to 15% of AI content to prevent false positives.
However, some educational institutions chose to disable the automatic AI content detection (case in point: Vanderbilt). The reason: false positives, especially in the case of texts written by non-native English speakers.
Verdict: If you’re looking for an AI detector tool, Turnitin is a viable option only if you’re an educator at an institution that already uses it for checking assignments. If you’re a student and have access to Turnitin, you won’t be able to see your AI score.
Smodin
Pricing: Starts at $9/month (billed annually)
Target audience: Students, content writers, businesses, universities
Key features:
- Basic AI detection capabilities available for free (up to 5,000 characters, five free scans per week)
- Sentence breakdown available (premium users only)
- File upload for AI content detection (.docx, .doc, .pdf)
Smodin is an AI writing assistant for students and content creators alike that offers a free (albeit limited) AI detector. Unlike most tools on our list, however, Smodin can determine AI-generated content and human-written text only.
Here’s how Smodin fared in our testing:
- AI-generated content: Incorrectly labeled ChatGPT output as 28% AI-generated text and Claude output as 68% AI-generated, while identifying Gemini content as 100% AI-written content
- Human-written content: Correctly identified all three samples as fully human-written content
- Mixed content: Incorrectly identified all three texts that combined human-written and AI-generated passages as 100% human-written
Verdict: Smodin isn’t the most accurate AI detector out there. It tends to produce a lot of false negatives, and its limited free version leaves much to be desired. That said, you may find the file upload quite convenient.
Originality.ai
Pricing: Starts at $12.95/month (billed annually) or $30 as a one-time payment (pay-as-you-go)
Target audience: Content marketers, writers, publishers, website owners
Key features:
- GPT-4o, Claude 3.5, Llama 3.1, ChatGPT, and Gemini Pro content detection
- File upload and URL import (premium users only)
- Free lite checks for texts of up to 750 words
- Confidence score instead of AI-generated text share
Originality AI offers more than an AI content detection tool. The platform also comes with plagiarism detection and a fact checker, along with a Chrome extension, API integration, and even a WordPress plugin.
It is upfront about being built for content writers and website owners, not students. So, if you’re wondering how to make your essay not AI detectable, Originality AI is probably not the tool for you.
Here’s how Originality AI fared in our testing:
- AI-generated content: Correctly flagged AI-written content as 100% AI-generated
- Human-written content: Correctly identified human-written content in all three cases
- Mixed content: Incorrectly provided a 100% human-written confidence score for all samples
Verdict: Originality.ai is a good tool for verifying that your blog posts, website copy, and other online content are completely human-written.
It is recommended to read the Originality AI review to get more detailed information and insights before making a choice.
Winston AI
Pricing: Starts at $12/month (billed annually), free plan available
Target audience: Content writers, students, teachers
Key features:
- Legacy AI content detection for previous ChatGPT models
- Advanced AI model detection even on the free plan
- ChatGPT, Claude, Google Gemini, Llama, Jasper content detection
- Multi-language support across seven languages, including English, Spanish, and Chinese
Winston AI is an AI detector that can detect AI, human-written, and AI+human content. In addition to AI-generated text, Winston AI can also detect AI-generated images and deepfakes. Under its free plan, you can run a check on up to 2,000 words, but only while your free trial is ongoing.
Here’s how Winston AI fared in our testing:
- AI-generated content: Correctly identified all three samples as over 98% AI-generated
- Human-written content: Scored fully human-written samples as 94%, 96%, and 97% human
- Mixed content: Incorrectly scored the samples as almost fully human-written, with scores exceeding 95% in all three cases
Verdict: Winston AI offers you a wide range of features and relatively accurate results for purely AI-generated or human content. But if you’re looking for a free checker (even a limited one) you can use regularly, this tool isn’t it.
Undetectable AI
Pricing: Starts at $10/month (billed annually)
Target audience: Content writers and students looking to bypass AI checks
Key features:
- AI detection likelihood across multiple tools (including QuillBot, Grammarly, GPTZero, and Sapling)
- Overall human score and AI probability score
- AI humanizer available within the same interface
- Sentence breakdown of the probably AI-generated text
If you’re dismayed by just how disparate AI check results can be across multiple tools, Undetectable AI was created for you. It returns the AI detection likelihood score across multiple AI checkers, including some of the ones we mentioned on this list.
Here’s how Undetectable AI fared in our testing:
- AI-generated content: Correctly identified Gemini, ChatGPT, and Claude content with 95+% AI probability score
- Human-written content: Falsely flagged human-written samples as 58%, 61%, and a whopping 80% AI-generated
- Mixed content: Identified the AI content correctly, but mistakenly flagged some human-written paragraphs as AI-generated
Verdict: Undetectable AI is worth looking into if you’re an unapologetic generative AI user and want to make your use of tools like ChatGPT undetectable. That said, false positives are rampant with this tool.
Check also: The AI Detection FAQ page provides detailed information on AI detectors in education. Explore it!
In Closing
So, what is the best AI detector? Well, the final verdict depends on your particular needs. You might value free access above everything else, for example. Or, you might be willing to pay a subscription fee, but you’d want a detailed sentence breakdown and multi-language support.
That said, there is one AI detector that turned out to be the most accurate one in our testing: StudyAgent. So, if you’re looking for a dependable AI detector packaged into a powerful AI-powered academic writing tool, check it out!
Frequently asked questions
Accuracy changes as new AI models appear, but tools that combine multiple detection engines usually work best. For example, StudyAgent cross-checks results across different algorithms. That lowers the chance of missed signals or false positives.
The best AI detector is one that offers both precision and usability. Students often prefer platforms that break results down paragraph by paragraph, because this gives them a clear view of which sections may raise concerns.
Yes, AI detectors work, but their effectiveness varies. The stronger ones rely on constantly updated algorithms that keep up with evolving AI models.
Sources:
- Coley, M. (2023, August 16). Guidance on AI detection and why we’re disabling Turnitin’s AI detector. Vanderbilt University. https://www.vanderbilt.edu/brightspace/2023/08/16/guidance-on-ai-detection-and-why-were-disabling-turnitins-ai-detector/
- Survey: 86% of students already use AI in their studies -- campus technology. (2024, August 28). Campus Technology. https://campustechnology.com/articles/2024/08/28/survey-86-of-students-already-use-ai-in-their-studies.aspx
- Turnitin. (2024, October 18). Turnitin’s AI writing detection model architecture and testing protocol. https://www.turnitin.com/whitepapers/turnitin-ai-writing-detection-model-architecture-and-testing-protocol
