That’s where AI writing detectors come in!
These AI-powered tools are designed to analyze and evaluate written content to help you accurately identify AI-generated content.
In this in-depth review of the top AI writing detection tools, we break down what they are, how they work, the factors that influence their accuracy, and how accurate they really are.
We tested each tool hands-on using the same content samples to give you a clear, side-by-side comparison of their performance.
If you’re looking for reliable, human-user insights on which AI detectors deliver the best results, we’ve got you covered!
What is an AI Writing Detection Tool?.
An AI writing detection tool is a software application that analyzes written text to determine the likelihood that it was generated by an AI model rather than a human.
These tools are trained on large datasets of human- and AI-written content to identify patterns such as word predictability, sentence structure, and stylistic features.
By comparing these patterns, the tool assigns a probability or confidence score indicating whether or not the content is AI-generated.
Common use cases for AI writing detectors include:
- Education / Academic Originality: AI detectors like Turnitin are used to check if essays, assignments, or exam answers have been generated using AI tools like ChatGPT.
- Plagiarism Detection: Plagiarism detection tools help verify original, human-written work. Researchers and institutions may use detectors to uphold ethical guidelines on authorship in academic publishing.
- Editorial Compliance and Content Quality: Publishers and blog editors use detectors to ensure content meets originality standards and hasn’t been mass-produced by AI. Detectors also help publishers confirm whether AI use is being properly disclosed to uphold transparency requirements.
- Recruitment: Employers can use detectors to check whether cover letters, writing samples, or personal statements were genuinely authored by the applicant.
- Freelance & Content Platforms: Agencies or clients on platforms like Upwork or Fiverr can use detection tools to verify that writers are delivering human-authored content as promised.
In all of these use cases, AI detectors help verify the authorship and originality of written content by flagging cases where additional assessment may be required to meet the required standards.
How Do AI Content Detection Tools Work?.
In simple terms, AI content detection tools analyze patterns in written text to assess the likelihood of it being generated by an AI model rather than written by a human.
AI copywriting tools generate content by predicting the next word in a sentence based on patterns learned from the datasets they were trained on.
As a result, AI-generated text often shows statistical regularities, such as high fluency, low variance in sentence structure, and predictable phrasing.
Large language models (LLMs), like ChatGPT, are trained on massive datasets, allowing them to base their predictions with a high level of accuracy.
However, they’re still fairly predictable because the sentence structure (sequence of words used) is based on a pattern that is, well, predictable.
Most AI writing detector tools are AI models themselves, trained using machine learning algorithms, similar in architecture to the language models they aim to detect.
They’re trained on large datasets of both human-written and AI-generated text to recognize the statistical and stylistic patterns that distinguish the two.
For example, they might detect differences in sentence variety, word predictability, or how concepts are developed throughout a passage.
Some detectors use classifiers (like logistic regression or neural networks), while others rely on perplexity scores, which are a measure of how “surprised” a model is by a given sequence of words. Lower perplexity scores usually indicate that the text is AI-generated.
How Accurate Are AI Writing Detection Tools? .
Recent studies show that some leading AI-writing detection tools can achieve over 90% accuracy.
However, an academic review of 14 detectors published in the International Journal for Educational Integrity in 2023 found that less than half achieved more than 70% accuracy overall.
The level of accuracy reported varied most between unedited, fully AI-generated text and content that was paraphrased or edited by humans.
Some tools also show high false-positive rates, particularly for non-native English writers.
While AI detectors are incredibly valuable for anyone who needs help verifying the originality and authenticity of a written text, they’re not foolproof.
What Factors Influence the Accuracy of AI Writing Detection? .
The accuracy of AI detection tools depends on numerous factors relating to both the characteristics of the text and the capabilities of the tool itself.
- How long the text is: Short text provides fewer data points for the detection tool to work with, making it harder for the model to identify consistent patterns for its analysis.
- The version of the AI model used to generate the text: If the data used to train the tool is limited to outputs from older versions of an AI model (e.g., GPT-2), it may be less accurate for content from newer models (e.g., GPT-4 or beyond).
- Human editing of the AI-generated text: Human revisions, like manual editing or paraphrasing, make it more difficult to accurately identify as AI-generated.
- Writing Style and Complexity: Simple, formulaic writing is more likely to be flagged as AI-generated, due to factors like low sentence variety or high predictability, while more sophisticated and complex texts may avoid detection.
- The training methods and data used: The quality, size, and diversity of the dataset used to train a detection model significantly impact its accuracy.
- Language and Domain Specificity: Detection tools may be less accurate when analysing writing for specialized fields, like legal or technical writing, or in a different language if they haven’t been adequately trained for that.
- Use of AI Paraphrasing Tools: If AI paraphrasers or text spinners are used to significantly alter the sentence structure, tone, and writing style, it is more difficult for the detection tool to identify them as AI-generated.
With so many variables, it’s almost impossible for any detector to be completely accurate for every use case, in every context.
That said, like all AI algorithms, they will continually improve as the datasets they’re processing expand with use and additional training.
How We Tested the Top Detect AI Writing Detectors.
To find the best AI writing detectors available, we looked at dozens of the tools available, existing software reviews, and did some Reddit deep dives to get perspectives from actual users.
From there, we chose the tools that looked the most promising and set about testing them to see how accurate they were.
We tested them using variations of a 1500 word text:
- Completely original human-written text: We took content from our own, 100% original and human-written, Employee Advocacy Platforms article to use for the tests.
- Unedited, fully AI-generated text: We gave Claude a simple prompt to produce blog post content covering the same points covered in our human-written sample.
- Edited AI-generated text: We took the fully AI-generated content that Claude produced for this test and edited it to fit our content style and tone.
We wanted to provide a simple, apples-to-apples comparison, so we used the same writing samples to test each tool.
As we’re in the marketing niche, we used marketing-related samples, which, of course, limits our testing and test results to those applicable to this type of content.
Accuracy results could be very different for content in more specialized things like legal, technical, or academic writing.
We recommend that you run some of your own tests if you’re looking for a more specialized tool (like Turnitin, which is specifically for educational institutions).
5 Best AI Writing Detectors Based on Our Test Results.
Here are our detailed reviews of the tools we tested, including the test results and our observations and experience using them, as well as their key features and pricing:
1. ZeroGPT.
ZeroGPT is a free, web-based AI detector that analyzes submitted text to determine whether it was written by a human or generated by an AI model like ChatGPT, GPT‑4, Claude, or Gemini.
It uses advanced natural language processing techniques and machine learning algorithms trained on large datasets of both human-written and AI-generated content.
After submitting your text, ZeroGPT provides the percentage of AI-generated vs human-written text and highlights the detected origin at the sentence level, so you can see exactly which parts of the text it is basing its analysis on rather than just a general overall score.
ZeroGPT offers several additional tools, including a paraphraser, summarizer, plagiarism checker, and grammar/spell checker.
ZeroGPT’s Test Results.
ZeroGPT was very easy to use by simply pasting your text into the box and clicking the ‘detect text‘ button.
It did its analysis quickly, highlighted the sentences it flagged as AI content, and provided a percentage score indicating how much of the text was identified as being AI-generated.
The results were pretty accurate:
- Unedited Fully AI-generated Text: 99.04 % of the text is AI-generated
- Fully Human-Written Text: 27.46% of the text is AI-generated
- Edited AI-generated Text: 95.21% of the text is AI-generated
It accurately identified the fully AI-generated, unedited text as AI/GPT writing and, clearly, the edited version of the AI-generated text wasn’t fooling ZeroGPT either!
It did pick up a false-positive of ‘27% AI-generated text’ in the fully human-written sample, but the highlighted sentences made it easy to check the sections it was flagging.
ZeroGPT’s Features & Tools.
- AI Writing Detector
- AI ZeroChat-4 & 5
- AI Plagiarism Checker
- AI Summarizer
- AI Paraphraser
- AI Grammar Checker
- AI Translator
- Word Counter
- AI Email Helper
ZeroGPT Pricing.
- Free: Free forever (no credit card required)
- Pro: $9.99 per month
- Plus: $19.99 per month
- Max: $26.99 per month
- ZeroGPT offers a 30% discount on annual plans
Website: https://www.zerogpt.com/
2. Originality AI.
Originality AI is a robust solution designed for publishers, marketers, and content creators. It combines AI-generated content detection, plagiarism checking, readability scoring, and fact-checking within one platform.
It offers AI writing detection for content from recent models like GPT‑4, Claude, and Gemini, for both fully AI‑generated and paraphrased text, such as content processed through text spinners and paraphrasing tools.
Originality AI also offers team management features, API access, a Chrome extension, and a useful website scanning tool to audit published web content for AI-generated content and plagiarism.
Originality AI’s Test Results.
The free AI detector has a 750-word limit (you can buy additional credits once off or get a paid subscription), so we just used the first 750 words of each of our three samples for this test.
It was easy to use – just paste the text in and hit ‘scan’, and it gives you a % score, and highlights the text provided in different colours, showing the sections they’re most confident in are AI-generated.
The test results were pretty accurate:
- Unedited Fully AI-generated Text: 100% confident this is AI-generated text
- Fully Human-Written Text: 100% confident this is original text
- Edited AI-generated Text: 93% confident this is AI-generated text
Originality AI’s score of 93% confidence that the edited AI-generated text was written by AI shows that it wasn’t fooled by our editing, and it did pick up that the text was not fully AI-generated.
Here is what the test result looked like, with the color-coded highlights showing its assessment of different sections of the text:
Overall, Originality AI was easy to use and highly accurate, although the free tool was limited to 750 words at a time, which is a downside for anyone who only wants to use the AI detector and not the full suite of Originality AI’s features.
Originality AI’s Features & Tools.
- AI Checker
- Plagiarism Checker
- Fact Checker
- Readability Checker
- Grammar Checker
- AI Humanizer
- Content Optimizer
- Bulk Scanner / Website Auditing Tool
- API
- WordPress Plug-in
- Chrome Extension
Originality AI’s Pricing.
- Free Trial: Yes
- Pay As You Go: $30 once off for 3000 credits (100 words per credit)
- Pro: $14.95 per month for 2000 credits
- Enterprise: $179 per month for 15000 credits
- Full functionality for all plans, but Pro and Enterprise offer additional features and support.
- Annual plans get up to a 23% discount.
Website: https://originality.ai/
3. Surfer SEO’s Free AI Detector.
Surfer SEO is an AI-powered content optimization platform designed to help marketers, content creators, and SEO professionals write high-ranking articles based on real-time search data.
It analyzes top-performing pages for a given keyword and provides on-page SEO recommendations—such as word count, keyword usage, structure, and headings—to improve content visibility.
Surfer SEO is ideal for businesses, agencies, and individuals who want to streamline their SEO workflows, create data-driven content, and improve organic search performance.
In addition to Surfer SEO’s many content creation and optimization features, it offers an easy-to-use free AI detector!
Surfer SEO AI Detector’s Test Results.
Surfer SEO’s free AI detector is super easy to use – you just paste the text in and it gives you the percentage likely written by AI and the percentage likely written by a human in seconds.
And it was highly accurate:
- Unedited Fully AI-generated Text: 100% AI and 0% human-written
- Fully Human-Written Text: 0% AI and 100% human-written
- Edited AI-generated Text: 46% AI-generated and 54% human-written
Overall, it was super simple to use, it took the 1500-word text with no problem, it was really quick, and it was very accurate!
Surfer SEO Features & Tools.
- Free AI Detector
- Free AI Humanizer
- Free AI Writing Tools
- Content Editor
- Topical Map for Content Ideas
- Content Audit
- Surfer AI
- Keyword Surfer Chrome Extension
- Content Editor Extension for Google Docs or WordPress
- Grow Flow AI growth tool with keyword-driven weekly tasks
Surfer SEO’s AI Detector Pricing.
- Free
- Check out Surfer SEO’s pricing page for details on their premium services.
P2P Score: 4.8/5
Website: https://surferseo.com/ai-content-detector/
4. Grammarly’s Free AI Detector.
Grammarly a well-known writing assistant tool, combines advanced grammar and spell checking with AI-driven style suggestions, plagiarism detection, readability insights, and now AI‑text detection.
Grammarly’s free AI detector analyzes your document and gives you a percentage score of the AI content identified.
If you download Grammarly and subscribe, it will break the analysis into sections when scoring the proportion likely generated by AI, underlining flagged passages, and providing more details.
It also integrates with Grammarly Authorship, which tracks how much text is typed, pasted, AI‑generated, or edited within the tool, offering a transparent report on authorship.
While its AI detection aims to support responsible writing, Grammarly acknowledges it is probabilistic and not definitive, often encouraging users to review flagged content thoughtfully.
Grammarly’s Free AI Detector
Grammarly’s Free AI Detector’s Test Results.
Grammarly’s free AI detector was easy to use by simply pasting in the text and clicking the button.
However, it had a 10 0000 character limit, so we had to delete some of the content in the fully AI-generated sample, and it took a bit longer to do the analysis than some of the other tools.
The results were mixed:
- Unedited Fully AI-generated Text: 63% AI
- Fully Human-Written Text: 0% AI
- Edited AI-generated Text: 54 %
Grammarly accurately identified the human-written sample as having 0% AI-generated text, and picked up 54% AI-generated text for the sample we’d edited, which is more or less in line with what the other tools we tested, but it only found 63% for the fully AI-generated, unedited sample.
Overall, Grammarly was easy to use (and free), but it wasn’t quite as accurate as some of the other tools we tested.
Grammarly Features & Tools.
- AI Detector (free, limited to 10,000 characters per check)
- Spelling and Grammar Checker
- Plagiarism Checker
- AI Humanizer
- Citation Generator
- Essay Checker
- Paraphrasing Tool
- AI Writing Tools
- Tone Detector
- Word Counter
- Character, Sentence, and Paragraph Counter
- Style Guide
- Snippets
- Analytics
- Brand Tones
- Authorship
- Grammarly for Windows, Android, and iOS
Grammarly’s Pricing.
- Free Forever: Spelling and grammar checker + limited app functions and AI writing prompts
- Premium: $30 per month
- Business: $25 per member, per month
- Enterprise: Custom Pricing
- Discounted Annual Plans: $12/month for Pro and $15/member/month for Business
Website: https://www.grammarly.com/ai-detector
5. Copyleaks.
Founded in 2015, Copyleaks was developed with the aim of safeguarding intellectual property, upholding academic integrity, and governing responsible AI adoption.
Copyleaks is widely recognized as one of the most accurate detectors available and provides advanced detection of AI-generated and plagiarized text across 30+ languages.
It detects content from major LLMs, including ChatGPT, Gemini, and Claude, and flags paraphrased or plagiarized material.
The platform also offers API and LMS integrations, Google Docs and Chrome extensions, and features like AI Source Match and AI Phrases that highlight why specific content was flagged.
Copyleaks
Copyleaks’ Test Results.
Copyleaks is a comprehensive tool, and after logging in, you have a dashboard with numerous options, from pasting text to uploading files or entering a URL.
Interestingly, it offers three levels of sensitivity for AI detection: text pasted straight from an LLM like ChatGPT, text that has been lightly edited, and text that has been heavily edited.
We chose level 3, the most ‘sensitive’ level, for our tests.
The test results were very accurate:
- Unedited Fully AI-generated Text: 100% of the text is AI-generated
- Fully Human-Written Text: 100% confident this is original text
- Edited AI-generated Text: 93% confident this is AI-generated text
Overall, Copyleaks is a nice tool to use, and it is clearly designed for users who need in-depth analysis and detailed information on the results they get.
The scanner is also a text editor, so you can edit and re-scan as you go, and you can scan for plagiarism at the same time.
Copyleaks also offers really useful features like sharing and exporting the analysis report from within the platform.
It looks like a really solid choice for publishers, educational institutions, and anyone else who is handling a large volume of content and needs a comprehensive solution.
Copyleaks’ Features & Tools.
- AI Writing Detector
- Plagiarism Checker
- Writing Assistant
- API
- LMS integration
- Browser Extension
Copyleaks’ Pricing.
- Free Trial:
- AI Detector: From $9.99 per month for 100 credits (250 words per credit)
- Plagiarism Detector: From $10.99 per month for 100 credits
- AI Detector + Plagiarism Detector: From $16.99 per month for 100 credits
- Pricing is based on the number of credits (up to 30,000+ credits monthly)
- Annual plans get two months free
Website: https://copyleaks.com/
Final Thoughts on How to Identify AI-Generated Content .
After testing the top-rated tools, we can confidently say that no AI writing detector is perfect, but we were impressed with the results they achieved.
Accuracy is affected by so many factors that it’s almost impossible for any tool to be 100% accurate, 100% of the time.
That said, they’re still incredibly useful for identifying content that is likely AI-generated!
Understanding how they work will help you choose the right solution for your needs and inform how you use it as part of your broader content review process.
How can you identify AI-generated content?.
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