AI has become an integral part of our lives. We use it for everything, from writing a memorable happy birthday message and generating ideas for home remodeling to troubleshooting and boosting creativity and productivity at work. This is undeniable. Research estimates that between 500 and 600 million people are using AI tools on a daily basis.
We love artificial intelligence because it has evolved tremendously in the past years. It has evolved to a point where it’s becoming more and more challenging to distinguish the content produced by humans from the one generated by AI. Whether that’s good or bad is ultimately for you to decide. But the truth is that the content written by AI can now accurately replicate various human writing styles. Does this mean we can’t tell them apart anymore? Not necessarily.
What Are AI Text Checkers
So, do you want to know if a text is human-generated? Do you want to verify its authenticity? Enter AI content detector tools – programs designed to analyze text and estimate the probability of it being generated by an AI model, like ChatGPT or Gemini, rather than a human writer.
How do these tools work? Well, they rely on Large Language Models (ironic, right?) to identify certain patterns that distinguish AI-created text. There are two key metrics that are being assessed in the process: perplexity and burstiness.
Perplexity is essentially how predictable or random the next word in a sentence is. AI-generated text often has low perplexity because it’s trained to choose the safest, most common next word. On the other hand, a human can always say something unpredictable.
Burstiness measures the rhythm and variety of sentence length and structure. AI sentences have low burstiness, because they usually tend to have the same length and complexity. Human writing is not uniform. It may use a mix of long and short sentences, simple and complex phrases to create a natural stylistic variation.
How We Tested the Tools
To test these tools, we used a mix of AI- and human-written text. We asked ChatGPT to provide a personal and brief social media post about overcoming an awkward issue with a co-worker. We then asked it to refine it, so that it sounded more natural and human. Afterwards, we edited the text and added paragraphs of our own. Lastly, we wrote an original text about having to deal with a difficult situation in the workplace.
There are many tools on the market designed to identify AI-written content. Are they all equally accurate? Sadly, not. Some can offer relevant results, but there are also others that struggle to differentiate human from AI writing. Human sentences, particularly those that use formal or repetitive language, risk being incorrectly identified as AI content.
In this article we’ve compiled a list of the best solutions you can currently find to properly identify AI-generated content. Let’s take a closer look:
Winston AI
Winston AI is an AI content detector software with a claimed 99.98% accuracy rate. The platform can help educational institutions by ensuring authentic academic papers, online businesses rank higher in SERPs by maintaining content originality, as well as professional writers by enhancing efficiency and overall quality. For those purposes, it places at your disposal multiple tools: AI text and image detectors, plagiarism and fact checkers and a writing feedback tool to improve your content.
How does everything work? Winston AI detects robot-generated writing using a combination of methods, primarily relying on advanced machine learning and linguistic analysis. The software is trained on human-generated writing and on content created with popular LLMs like ChatGPT, Claude, Google Gemini and Llama. It analyzes elements like perplexity, burstiness and word predictability and, based on those factors, it returns a Human Score (0-100%). The tool also offers an AI Prediction Map, which highlights the specific sections of the text that may be AI-generated.
The dashboard is quite intuitive. Once you’ve registered, simply select the option to start content scan and load your text. You can copy/paste it, upload a file (.docx, .pdf, .jpg, .png, .tiff) or import text from a URL. The software will then scan your content and display the Human Score, Plagiarism and Readability Score.
Test Results
- It detected the initial text created by ChatGPT as 0% human.
- It detected the second text refined by ChatGPT, again, as 0% human.
- It detected the text written by ChatGPT and edited by us as 0% human. However, the prediction map provided a 57% human score to the sentences we added to the text.
- It detected the text we wrote as 100% human-written.
Pros
- Impressive accuracy when it comes to detecting both AI- and human-written text.
- User-friendly interface.
- OCR technology to extract text from scanned documents and images.
- Useful tools to ensure content and fact originality.
- Seamless integration with multiple browsers, apps and tools.
Cons
- Accuracy issues – it classified the AI-text we edited, adding original sentences, as pure AI.
- It sometimes froze during the text analysis.
Pricing
By creating an account, you get a 14-day, 2,000-word scan trial free of charge. The writing feedback, fact and plagiarism checker tools aren’t included in this free trial. Once the period expires, you can choose between three paid plans:
- Essential AI – $10/month
- Advanced – $16/month
- Elite – $26/month
QuillBot
QuillBot is an AI-based writing assistant designed for a wide range of projects. Whether you need help detecting AI content, writing a cold email, improving your college essay or rewriting an existing article, this platform is your ally. QuillBot is equipped with numerous tools for content creation and detection. These include a paraphraser, summarizer, grammar checker, plagiarism checker and, of course, an AI detector and humanizer to make text sound more natural.
When it comes to content detection, the process is quite smooth. Once you’ve accessed this specific feature, all you have to do is add the piece of text you’d like to be analyzed. You can either paste it or upload a document file. The software will then evaluate the writing and present a probability score that suggests three possible sources: AI-generated, human-written and AI-refined and human-written.
How does the evaluation occur? QuillBot uses a detector trained on a vast set of human- and AI-generated writing. The software isn’t designed to flag individual words. Instead, it analyzes repetitions, variations and language tone to detect machine-characteristic writing styles.
Test Results
- It declared the initial text created by ChatGPT as 95% AI-generated.
- It declared the second text refined by ChatGPT as 70% AI-generated.
- It declared the text written by ChatGPT and edited by us as 29% AI-generated and 71% human-written.
- It declared the text we wrote as 100% human-written.
Pros
- It performs well when it comes to recognizing content obviously written/refined by AI.
- Easy to work with.
- Useful additional writing tools for various use cases.
- Up to 1,200 words per scan in the free version.
Cons
- The results may not be optimal when the AI content has been moderately or heavily edited.
- Minor inconsistencies, such as not highlighting AI text uniformly.
Pricing
QuillBot comes with a free version, which allows you to scan texts of up to 1,200 words.
The Premium version costs $8.33/month and provides additional features, including the unlimited use of the Humanize text mode.
Originality.ai
Originality.ai is an alternative that stands out through its multiple AI detection models. Users have the possibility to select a model based on their specific use case:
Lite
- suitable for writers and editors
- it allows some AI editing
- it has a 99% accuracy in detecting AI content and 0.5% false positive rate
Turbo
- suitable for professionals
- it has a zero tolerance policy against AI use
- it has a 99%+ accuracy rate and AI sensitivity and 1.5% false positive rate.
Academic
- suitable for students and teachers
- it has a 99%+ accuracy at detecting AI-generated content and less than 1% false positive rate
So, which are the detection methods? Just like other tools, this one too examines key indicators like perplexity and burstiness, but it doesn’t stop there. Originality.ai relies on its internally-built artificial intelligence. The software uses advanced neural network architectures, such as modified versions of the BERT and RoBERTa models, in order to identify text that deviates from natural human writing.
The tool uses a confidence score to communicate its findings. The result is presented as a percentage breakdown showing the model’s confidence that the content is original (human-written) versus likely AI. Importantly, if the software says it is 100% confident that text is AI-generated, it doesn’t automatically mean that 100% of that text is produced by AI.
Test Results
It’s worth mentioning that we used the Lite model for testing.
- The software reported it is 100% confident that the initial text created by ChatGPT, the second one refined by the machine and the third one which we edited are AI-generated.
- The software reported it is 100% confident the text we wrote is 100% original (human-written).
Pros
- Clear, easy-to-use interface.
- Accurate detection of content written and refined by AI.
- Detailed reports, with a probability score for each sentence.
- It offers a comprehensive suite of tools, from AI detection to content optimization and plagiarism and readability checkers.
- The pay-as-you-go model can be a convenient solution for some users.
Cons
- It doesn’t clearly state which percentage of the text is AI-generated and which is human-written (at least in the Lite model).
- Originality.ai doesn’t a provide a free version or trial period. This makes it the least user-friendly solution from a testing perspective.
Pricing
Once you access the website, you get only 3 free checks. Afterwards you’re forced to sign up and choose one of the 3 paid plans:
- Pay as you go – $30 one-time payment
- Pro – $12.95/month
- Enterprise – $136.58/month
GPTZero
GPTZero reports a 99% accuracy rate when it comes to identifying AI-written text. How does it accomplish this rate? The platform relies on its own proprietary model which takes a multitude of factors into account when analyzing content. The software uses core statistical metrics to evaluate text predictability and variation, deep learning, a sentence-by-sentence classification model and additional models, such as its Paraphraser Shield, to improve accuracy and reliability.
Who is it for? GPTZero was developed by Edward Tian, a student at Princeton University, with the goal of combating AI-produced content in the academic environment. Besides educational institutions, the tool can also be put to use by copywriters, marketers, recruiters and businesses who place great importance on original and authentic content.
GPTZero is equipped with an advanced AI scan feature, indicating which sentences are impacting your AI/Human probability score. There are also features to discover words overused by AI models, to verify sources for citations, grammar and plagiarism checkers, as well as an AI grader for quick essay grading.
Test Results
- For the initial text created by ChatGPT it provided a 100% AI-generated score.
- For the second text refined by ChatGPT it, again, provided a 100% AI-generated score.
- For the text written by ChatGPT and edited by us it provided a 0% mixed score. It considered the whole text as AI-generated.
- For the text we wrote it provided a 100% Human score.
Pros
- High accuracy when it comes to detecting pure AI writing.
- The advanced scan feature for in-depth analysis.
- Useful extra options for students, teachers and writers.
- A fairly generous free tier.
Cons
- It can fail to detect the human intervention in an AI-written text.
Pricing
GPTZero comes with a free version, which lets you scan up to 10,000 words per month. You get 5 free advanced scans and basic AI scan.
There are three paid plans:
- Essential: $99.96/year
- Premium: $155.58/year
- Professional: $299.98/year
ZeroGPT
Even if it’s our last proposal, ZeroGPT is an AI content detector tool that deserves a spot on your radar. This online platform places at your disposal a quick, uncomplicated way to check pieces of writing for AI influence. All you have to do is paste the selected text directly in the main page of the website and get the results without creating an account.
ZeroGPT uses complex algorithms – which it calls DeepAnalyse™ Technology – to evaluate text. This system estimates the likelihood that the content was written by a human or generated by an LLM like those powering ChatGPT, Gemini, or DeepSeek. The software implements deep learning models that are trained on millions of human and AI-written texts to learn the subtle differences in linguistic patterns. The analysis of linguistic patterns includes sentence structure and length variation, word frequency and predictability, grammar precision and the level of emotional depth.
In addition to its AI detector, ZeroGPT is equipped with other practical features for educators, students or writers. The platform offers a Plagiarism Checker to verify content originality against billions of online sources. For text editing, it provides an AI Paraphraser, a Summarizer and Grammar Checker to help you refine and improve written content. You’ll also find an AI email helper for quick email replies and its own chat model called ZeroChat.
Test Results
- It identified the initial text created by ChatGPT as 100% AI-generated.
- It detected the second text refined by ChatGPT, again, as 100% AI-generated.
- It detected the text written by ChatGPT and edited by us as 23.43% AI-generated.
- It detected the text we wrote as 5% human-written.
Pros
- It accurately detects AI-produced writing.
- Simple, easy-to-navigate UI.
- You can use it without registering.
- A generous free plan, with numerous text checks available.
- Its features are available within WhatsApp and Telegram.
Cons
- False positive issue – it labeled the text which we created from scratch as 95% AI-written.
- We noticed some discrepancies during our tests. For example, the text refined by ChatGPT was flagged as 100% AI-generated, even though the tool also stated that “Your text contains mixed signals, with some parts generated by AI/GPT.”
- The ads in the free version can be quite intrusive, covering the menu.
Pricing
ZeroGPT offers a free plan with 15,000 characters per AI detection and a limited number of words for its AI plagiarism checker, summarizer, paraphraser and grammar checker.
There are three paid subscriptions, which provide more characters/words per scan and additional features:
- Pro: $7.99/month
- Plus: $14.99/month
- Max: $18.99/month
Bottom Line
Is there a single tool that can recognize AI-generated content with 100% accuracy? The honest answer has to be no (for now). The efficiency of the software is seriously put to the test when the text is carefully edited or rewritten by humans. Subtle changes, designed to “humanize” the content, can make the detection work truly challenging. Even so, these tools are truly useful for spotting AI involvement and providing valuable insights into content authenticity. The way things are looking, they’ll almost surely evolve and become significantly better at determining how a piece of content was created or refined.