AI detection tools, trained on both AI and human-generated content, can be used to determine the likelihood of AI involvement in content creation.
They primarily do this by comparing the provided content with their training material, focusing on subtle aspects like writing style, vocabulary, and grammar to predict the probability of AI generation.
But there is a notable nuance in how a detector goes about this.
There are four main AI detection methods, each with a different focus—this means that some AI detectors can be more accurate than others.
To save you the trouble of finding which AI detector is best, I signed up and tested 9 of the best AI detection tools that help identify artificially generated text.
1. Surfer AI content detector
Surfer's AI detector analyzes your text for patterns in style and tone, using machine-learning algorithms to generate a probability score indicating how likely your content is to be human or AI-written.
To get your results, you only have to paste your content (a minimum of 100 words) into the text box and give Surfer's AI detector a few seconds to work its magic.
In the above screenshot, Surfer accurately recognizes a segment of an article I had previously written as human.
The results include a clear, conclusive statement on whether the content is likely AI-generated or human-written, along with a percentage score showing the exact probability for each.
Any score above 50% will classify the text as AI-generated—but this is a grey area, so it's important to use your judgment as well.
Here’s how it performed in a real, unbiased test when I fed Surfer's AI detector with human-written, AI-generated, and mixed content:
- AI-Written Content: Surfer correctly identified three separate pieces of content generated by GPT-4o, Gemini, and Claude as AI-written, with an average AI probability score of 98%.
- Human-Written Content: It correctly identified three separate pieces of human-written content as human-written, with an average AI probability score of 12%.
- Mixed Content: Surfer also correctly identified a mixture of AI-generated and human content, with an AI probability score of exactly 50%.
Surfer's AI detector is free to use for content up to 500 words at a time.
For higher limits, you can sign up for the Essential plan, which offers unlimited AI detection along with a range of other SEO features.
2. QuillBot's AI detector
Among QuillBot's suite of popular paraphrasing and text optimization features is a pretty capable AI content detection tool.
There's no sign-up process, which is always a plus—you can immediately start detecting by either pasting your written content into the text box or uploading the document directly as a PDF.
QuillBot has a few different ways it classifies your text as human or AI-generated, a change from the general AI-or-not score other detectors go with.
You get an overall percentage of how likely the text is to be AI-generated, and then a breakdown of the score across different categories:
- AI-generated
- AI-generated & AI-refined
- Human-written & AI-refined
- Human-written
You can also detect text in Spanish, German, and French, though you won’t receive the same detailed score analysis as you would with English content.
But all the features in the world won't make an AI detector worth considering if its results aren’t reliable—here’s how QuillBot measured up:
- AI-Written Content: Correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an average AI score of 91%.
- Human Written Content: Quillbot correctly identified all three human-written articles as human, with an average AI score of 10%.
- Mixed Content: Quillbot failed to recognize the mix of human and AI content, incorrectly classifying the text as 0% AI.
It performed quite well, but like all AI detection tools, QuillBot isn't infallible. I recommend using it to get a general sense of whether your content is human-written, but never as definitive proof.
As for pricing, QuillBot is free to use if you’re okay with detecting a maximum of 1,200 words at a time.
If not, they offer a Premium plan priced at $4.17 per month, which allows for AI content detection of up to 25,000 words each month.
3. Turnitin AI checker
Turnitin, in addition to being a plagiarism checker, is an AI detector widely used in academia. Accounts are only available to institutions, instructors, and students.
It is quite a popular tool to detect AI generated content among teaching staff, since the incentive to avoid AI detection may be higher and more frequent in academic institutions.
Upload your document to Turnitin and provide a few essential details, like your region and the document title, to start detecting AI content.
It's not the fastest AI detection tool—even relatively small documents can take up to a minute to analyze.
But once it's done, you can see the overview of your results on the dashboard.
This includes the word count, similarity score, AI score, and a few other relevant details about the document.
For a more in-depth look at your AI score, click the PDF option next to the AI overview on your dashboard to download the detailed report.
Here, you’ll get a breakdown of the score, including the percentage of the document that is AI-generated and the portion that’s been AI-generated but paraphrased with another tool.
Scrolling down, you'll also see exactly which segments of your text Turnitin detected as AI.
Turnitin's detector has been trained on academic sources, so it delivers the most accurate results with documents that are also academic in nature.
But it's not too shabby with other forms of writing either, here are the results:
- AI-Written Content: Correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an average AI score of 98%.
- Human Written Content: Turnitin correctly identified all three human-written articles as human, with an average AI score of 13%.
- Mixed Content: Turnitin failed in this case and did not identify the mix of AI and human content, incorrectly labelling it as AI-generated with a probability score of 87%.
Turnitin doesn't have its pricing publicly listed. To set up an account, you'll have to contact the sales team to get a quote.
4. Hive AI moderator
Hive is another online AI detection tool.
Along with detecting AI-generated text, Hive also offers tools to detect AI-generated images, videos, and even audio.
To start off, enter your content into the text box—a minimum of 750 characters, though Hive recommends at least 1,500—then click submit.
Like with the other detectors I've discussed, you get an overall AI score, plus a segment breakdown highlighting which parts of your text show the most AI influence.
Hive's AI detection tool also comes with a Chrome extension, allowing you to analyze content directly on web pages, saving you the hassle of constantly juggling between tabs.
Keep in mind, though, that the browser extension limits AI detection to only up to 2,048 characters (roughly just a few paragraphs of content), which isn’t very practical unless your needs are just as minimal.
Moving on to the test, here's how Hive performed:
- AI-Written Content: Correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an average AI score of 99.9%.
- Human Written Content: Failed to recognize two out of the three human-written articles, incorrectly labeling them as AI-generated, and produced an average AI score of 78%.
- Mixed Content: Hive failed to recognize the mix of AI and human content, labeling the content human, and giving it an AI probability score of 12.7%.
Hive very confidently identifies AI-generated content, which is great. The downside, however, is that it's just as confident when it's wrong.
It is free to use and doesn’t come with any paid options—so what you see is what you get, with no hidden pay-to-unlock features.
5. Ahrefs AI content detector
The Ahrefs AI content detector is among the platform’s many free SEO and writing tools.
The interface is simple enough to use—you don’t need to create an account or log in. Just enter your text into the provided box and click Analyze.
The detector and content humanizer are combined into one tool, so you’ll see options for generating different text variations and other features that might not immediately make sense.
You can safely ignore these extras.
It's extremely fast and doesn't take longer than a few seconds to generate a result.
But this is quickly overshadowed by the tool's rather large limitation: you can only enter around 300–350 words at a time.
This meant I couldn’t input the 1,000-word articles I had been otherwise using to test out the other AI content detection tools on our list. Here are the results I was able to generate within these constraints:
- AI-Written Content: Ahrefs correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an average AI score of 76%.
- Human Written Content: Ahrefs failed to recognize any of the three human-written texts, incorrectly labeling them as AI with an average probability score of 80%.
- Mixed Content: The tool failed here as well and incorrectly labeled the mix of AI and human content as AI-generated, with a probability score of 80%.
6. Leap AI
Leap AI is another free-to-use tool to detect AI generated content, among other things.
It offers the standard text box for pasting your content, along with options to upload a document directly or enter a link to a webpage.
Once the analysis is complete, Leap AI provides a percentage score estimating the likelihood of AI involvement, along with a brief conclusion on whether the content is classified as AI-generated, human-written, or somewhere in between.
You'll also get a brief overview of exactly which sentences from your text yielded a high score, but the full scan is locked behind a paywall.
Here's how Leap AI fared when I put it through the test:
- AI-Written Content: Leap AI failed to recognize content generated by GPT-4o and Gemini, incorrectly labeling them as human-written, with an average AI score of 32%. However, it did correctly identify Claude's text as AI-generated with an 80% AI score.
- Human Written Content: Leap AI correctly identified all three human-written articles as human, with an average AI score of 38%.
- Mixed Content: Correctly identified a mixture of AI-generated and human content, with an AI probability score of 49%.
But I also noticed that the results generated could be quite unpredictable.
For example, the mixed article containing both human writing and AI text initially generated a 49% AI probability score, which increased to 61%, then decreased just as wildly to 37% when I ran the same text through the detector again.
Leap AI is free to use without an account for up to two detections per day (20,000 characters each).
After that, you can sign up to get an additional five free detections (6,000 characters each). They also offer a paid plan for $7 per month that comes with higher limits and more features.
7. Smodin
Smodin has a fairly sparse look to it—just a simple text box for pasting your content, along with a few general details explaining the tool’s functionality.
You can also upload your document as a PDF, doc, or docx file, and the tool will automatically extract the text from it.
It supports quite a few languages, which is not something you usually see in many AI detector tools.
However, they do acknowledge that the AI probability score can vary depending on the language, and some may not produce the most accurate results.
As with the other tools, I put Smodin through the test with different types of text, here are the results:
- AI-Written Content: Smodin correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an average AI score of 81%.
- Human Written Content: Correctly identified all three human-written articles as human, with an average AI score of 12%.
- Mixed Content: Failed to recognize the mix of AI and human content. Incorrectly labeled it as human-written, with an AI probability score of 12%
Smodin is free to use for up to 5 detections (5,000 characters each).
For higher limits, you can upgrade to the paid plan for $15/month and get unlimited AI detections (15,000 characters each).
8. Winston AI
Winston AI is another popular option for an AI detector.
It works much the same way as the other tools on our list, but instead of showing an AI probability score, it gives you a Human score.
It’s a small difference, but it's easy to get confused if you’ve used other AI detectors before.
To get started you can paste in your content, upload it as a document, or enter a URL to the webpage.
Once the scan is done, you get directed to the results page.
Here, you get your human score and a brief statement indicating whether your content is likely to be AI-generated or human-written.
Scrolling down, you'll find a detailed, step-by-step breakdown of exactly which sections of your text Winston AI deemed artificially generated.
Different highlights indicate different meanings—green for human-written, yellow for possibly AI-generated, and red for AI-generated content.
Here's how Winston AI did when I put it through an accuracy test:
- AI-Written Content: Winston AI correctly identified content generated by GPT-4o and Gemini AI models, with an average human score of 33%. However, it failed with Claude and incorrectly labeled it as human written with a 68% human score.
- Human Written Content: Correctly identified two of the three human-written articles, with an average human score of 75%.
- Mixed Content: Winston AI did a decent job of identifying a mix of AI and human content, with a human score of 67%. But the score is still leaning slightly more towards AI-generated than a mixture.
Winston AI uses a credit-based system, where each credit equals one word.
Upon signing up, you get 2,000 free credits, enough to analyze a 2,000-word article. For additional credits, you’ll need to upgrade to a paid plan, starting at $19 per month.
9. Plagiarism Check
Plagiarism Check's AI detector (dubbed TraceGPT) is another tool designed to help differentiate between AI-generated and human-generated text.
Paste your text directly into the text box or upload your document to get started.
Once done analyzing, the tool provides a quick AI probability score directly on the website.
For a more detailed report, you can download the full analysis as a PDF.
Here you will find the score, along with your text highlighted in light or dark purple—light means it’s likely AI-generated, and dark means it’s almost certainly AI.
They claim to focus solely on detecting ChatGPT content, but it performed really well with content generated using other AI models as well. Here is the full rundown of my findings:
- AI-Written Content: Plagiarism Checker correctly identified all three articles generated by ChatGPT, Gemini, and Claude as AI-generated, with an impressive average AI score of 99%.
- Human Written Content: The tool was unable to identify any of the three human-written articles, incorrectly labeling them AI-generated with an average AI score of 69%.
- Mixed Content: Plagiarism Checker did a fairly good job at identifying a mixture of human and AI text, with an AI probability score of 62%.
Plagiarism Checker's AI detector is free to use for your first 1000 words, after which you can sign up for their paid plan for $2.99/month.
Conclusion
AI content detectors can help you get an idea of whether a piece of content is AI-generated or not.
But detectors have been notoriously called more wrong than right. I tested several AI tools to see if this claim held up.
As it turns out, it seems to be an exaggeration—at least when you're using the right tools.
Surfer's AI content detector managed to pass all of my tests with flying colors.
Does this mean you should rely solely on detectors to determine if content is original? No.
They can be useful tools, but they are, after all, only tools.
The final decision should always be based on your own judgment as you better understand context, nuance, and the subtleties of content that AI detectors trained on a limited data set might miss.
