10 Best AI Plagiarism Checker – Side-By-Side Comparison [2024]

The consequences of plagiarism can be severely damaging to a career or academic record – whether intentional or not.

Specifically, plagiarism…

  • … can ruin reputations
  • … affect academic integrity, and:
  • … lead to legal troubles (such as copyright infringements or breach of contract)

Sometimes, plagiarism can still haunt you years later when you least expect it, such as in the case of a German minister who was forced to resign amidst a plagiarism scandal.

It’s vitally important that academic as well as professional works are:

  1. Checked for plagiarism before they were submitted.
  2. Checked for AI before they’re submitted (which may be subject to plagiarism laws).

In the following article, you’ll discover the best plagiarism checkers that use artificial intelligence to detect plagiarism and/or AI-generated content.

Best AI Plagiarism Checkers: Side-By-Side Comparison

# Name of Tool AI Detection Conventional Plagiarism Detection Free Version
1 Undetectable AI Yes No Yes
2 Turnitin Yes Yes No
3 iThenticate Yes Yes No
4 CopyScape No Yes Yes
5 PlagScan No Yes No
6 Copyleaks Yes Yes No
7 Grammarly No Yes No
8 GPTZero Yes No Yes
9 GLTR Yes No Yes
10 Originality AI Yes No Yes

There are plenty of AI plagiarism checkers that you can use to check for AI-generated content and conventional plagiarism.

Sorting through them all may be tedious and time-consuming. That’s why we’ve done the work for you.

Here are the best options to safeguard your work in 2024:

  1. Undetectable AI – Best Overall AI Detector And Humanizer
  2. Turnitin – Good for Educational Institutions
  3. iThenticate – Good for Researchers
  4. Copyscape – Good for Blogs
  5. PlagScan – Good (Student) Alternative to Turnitin
  6. Copyleaks – Good Allrounder
  7. Grammarly – Good Alternative to Copyleaks
  8. GPTZero – Good User Interface
  9. GLTR – Good for Detecting Older AI-generated Content
  10. Originality AI – Good Overall AI Detector

In this post, we’ll compare and contrast the following in detail:

  • Key features and capabilities
  • Pricing (monthly and annual plans, free trials)
  • Reviews (customer reviews, online ratings from G2 and/or ProductHunt) 

1. Undetectable.ai – Best Overall AI Detector


Undetectable.ai is an award-winning AI detector with great AI plagiarism features. The AI tool has been featured in Business Insider, ABC, CBS, NBC, Yahoo Finance, Fox, Lifewire, and Nature.

As of February 2024, Undetectable AI is incredibly popular with over 5,000,000 users and a #1 AI detector rating by Forbes.

Undetectable AI allows users to detect AI-generated content at the click of a button. The AI detection is absolutely free.

Undetectable AI, however, does not conventionally check for plagiarism. So, it’s best used with the combination of a conventional plagiarism detector if it’s used by an educational institution.


  • Free AI detection: The tool is free to use for AI detection.
  • Easy to use: Instantly and effortlessly test for AI plagiarism without any need to give your contact details. 
  • Award-winning accuracy: Third-party tests report accuracy of 85-95%, making it one of the most accurate solutions available in 2024.


  • Does not check for conventional plagiarism.


5 out of 5 on ProductHunt


The AI plagiarism detection is absolutely free. Undetectable AI only charges for the concealing of AI content. 

Our ‘AI humanization’ plans start at $9.99/mo for 10,000 words – and range to $209/mo for 308,000 words if paid monthly (we offer a 50% discount on yearly packages). For enterprises with a need for a higher monthly word volume, we offer customized enterprise plans.

Click here to see our pricing in detail.

Additionally, we offer an iron-clad money-back guarantee. If we humanize (conceal) the AI content and it’s still detected – we will refund the cost of humanization completely.

Click on the link to detect your first AI-generated text for absolutely free.

2. Turnitin – Good for Educational Institutions


Turnitin is perhaps the most well-known plagiarism checker in the academic world. It is commonly used by educational institutions to ensure that the work of students is original.

Turnitin’s advanced algorithms compare submissions against an extensive database of academic papers, web pages, and publications to detect similarities and potential plagiarism.


  • Good conventional plagiarism checker
  • Contains AI detection.


  • Users complain about AI detection being inaccurate at times


4.3 out of 5 on G2


Turnitin’s pricing is not publicly visible on the page. Third-party sites mention $3 per student annually for educational institutions.

3. iThenticate – Good for Researchers


iThenticate is a product by the same company that created ‘Turnitin.’ It’s a professional plagiarism detection and prevention technology designed primarily for researchers.

Unlike other plagiarism-checking tools, iThenticate specializes in comparing academic papers against a massive database of over 60 billion web pages and 155 million content items, including leading journals, publications, and research articles.

This makes it particularly valuable for researchers and scientists looking to ensure the originality of their scholarly papers, reports, and grant proposals.

iThenticate is known for its accuracy, ease of use, and comprehensive reporting, making it a trusted tool in academic and professional communities for maintaining the integrity of their work.


  • Good plagiarism checker.
  • Good AI-generated content detector.


  • Users complain about plans being expensive.


4.8 out of 5 on G2


iThenticate charges a one-off payment of $100 per manuscript with 25,000 words and below. Or $300 for one manuscript with up to 75,000 words.

4. Copyscape – Good for Blogs


Copyscape is a favorite among website owners and online publishers. How it works is simple:

  1. Enter the URL of your content.
  2. Copyscape scans the web for any duplicates of the content.

Website and blog owners use the tool to avoid SEO penalization for duplicate content. It also allows an easy way to check for fraudulent use of their content (plagiarism).


  • Good conventional plagiarism checker for blogs and websites.
  • Offers an extensive free version.


  • Users complain about searches getting expensive quickly.


4.9 out of 5 on Capterra


The basic features of CopyScape are free to use. The pricing of the premium features is slightly complex. According to GetApp, ‘Copyscape Premium’ charges 3¢ per search (up to 200 words) plus 1¢ per extra 100 words. ‘Copysentry Standard’ charges $4.95/mo for up to 10 pages, plus $0.25/mo per additional page. And ‘Copysentry Professional’ charges $19.95/mo for up to 10 pages, plus $1.00/mo per additional page.

5. PlagScan – Good (Student) Alternative to Turnitin


PlagScan is a comprehensive plagiarism detection tool by the same company as Turnitin and iThenticate.

PlagScan offers detailed reports that outline not only instances of plagiarism but also potential sources, making it easier to address issues. PlagScan prides itself on its respect for data privacy, ensuring that your documents remain confidential.

It serves as a great alternative to Turnitin, as it’s not billed by students for educational institutions. Instead, it bills its users by word count.


  • Advanced plagiarism detection.
  • Billed by word count.


  • Users complain about a lack of integrations with third-party tools, such as MS Word.


4 out of 5 on G2


Users get billed based on the number of words that get checked for plagiarism. Plans start at $5.99 for 6,000 words and go up to $49.99 for 100,000 words.

6. Copyleaks – Good Allrounder


Copyleaks is an accurate AI detection software with additional plagiarism-prevention features.

The software uses sophisticated AI and machine learning algorithms to scan and compare documents against a vast database of online sources, academic papers, and proprietary content. 

Copyleaks does not offer users an easy way to test its software, as it requires payment to see the results.


  • Accurate AI detection.
  • Good plagiarism detection.


  • Difficult to use: Requires sign-up to get the results
  • Results are behind a paywall.
  • Users complain about the difficulty of canceling the plans.


4.4 out of 5 on Capterra


Prices range from $9.99/mo for AI detection only on 25,000 words to $16.99/mo for AI and plagiarism detection on 25,000 words. 

7. Grammarly – Good Alternative to Copyleaks


When most people think of Grammarly – they think of ‘grammar checker.’

Right? Well, turns out Grammarly has many more tools in its toolbelt! One of these is a powerful plagiarism detection feature.

It compares your text against billions of web pages and academic databases to identify potential plagiarism. Quickly making you able to check your text for plagiarism and cite your sources.

While Grammarly does not check for AI plagiarism, it is a great writing assistant for people who want to ensure their writing is not only error-free but also original.

It may be used in combination with accurate AI detectors such as Undetectable AI to check for AI-generated content and plagiarism.


  • Widely used software.
  • Offers a Chrome extension.


  • Requires premium version for plagiarism check.
  • Users complain about inaccurate suggestions at times.


4.7 out of 5 on G2


Grammarly has a free plan, yet for the plagiarism-checker you’d require one of its paid plans. They range from $12/mo for one user to $25/mo for a business/enterprise user.

8. GPTZero – Good User Interface


GPTZero is an AI-detector tool that offers additional features to humanize the content. GPTZero is similar to Undetectable.ai in that regard, as it offers accurate AI detection and humanization.

While GPTZero does not offer conventional plagiarism checks, its general AI detection is available for free and without sign-up. 

Overall, GPTZero shines with its beautiful design and its simple user interface.


  • Good AI plagiarism detection.
  • Beautiful design.


  • Requires sign-up (for advanced features, such as deep scan).
  • Does not offer conventional plagiarism checkers.


4.2 out of 5 on ProductHunt


Prices range from $15/mo for 150,000 words to $35/mo for 500,000 words.

9. GLTR – Good for Detecting Older AI-Generated Content


GLTR Is a free AI detection tool that can check for AI plagiarism for free.

GLTR is a research preview and stands for ‘Giant Language (Model) Test Room.’ The tool has direct access to ChatGPT-2 data, and as such, it works great for content generated with older versions of ChatGPT (2019).

Here’s how to interpret the test results created by GLTR (Giant Language Model Test Room):

  • Green word: The word is likely generated by AI
  • Yellow word: The word is probably generated by AI.
  • Red word: The word is probably not generated by AI.
  • Purple word: The word is not generated by AI.


  • Free AI detection.


  • No conventional plagiarism detection.
  • Optimized for GPT-2, it may not work as well for newer AI-generated content.
  • No clear percentage score, the tool requires knowledge of statistics to interpret the results.


No publicly available reviews so far of GLTR’. 


Giant Language (Model) Test Room (GLTR) is free to use.

10. Originality AI – Good Overall AI Detector


Originality AI is an online tool designed to detect AI plagiarism.

It aims to assist users, such as individuals or businesses, in identifying whether written content has been created by an AI – or a human.

Additionally, Originality AI also offers a built-in plagiarism checker. 

When it comes to AI detection, the software analyzes the content and provides a percentage score indicating the likelihood of the content being AI-generated. 

While Originality AI passed our test, we couldn’t access the full analysis of the content as it’s behind a paywall. 


  • Passes our AI test
  • Offers a Chrome extension
  • Free AI detection


  • Detailed results are behind a paywall.
  • Users complain about human-written content being marked as ‘100% AI.’


2.9 out of 5 on ProductHunt


Prices start at $14.95/mo, which allows you to check up to 200,000 words for AI. If you need to check additional words for AI, you can buy separate packages that start at $30 for 300,000 words. 

Frequently Answered Questions

Given that AI plagiarism is a largely new field and topic, there may be many questions related to identifying AI-generated content.

In this section, we’d like to respond to some of the most pressing ones:

What Is AI Plagiarism?

AI plagiarism refers to the act of using AI tools, specifically Large Language Models such as ChatGPT or Bard, to create content that is then presented as one’s original work.

This can occur in various contexts, including:

  • academic essays
  • articles
  • blog posts
  • research

How To Check For AI Plagiarism?

Checking for AI plagiarism involves a combination of conventional plagiarism detection methods and newer techniques, such as using an AI-content detector.

It’s important to note that AI-generated text can be highly original and may not directly match existing sources. That’s why AI plagiarism can be more challenging than detecting traditional plagiarism.

We recommend using an AI checker first and then using conventional plagiarism checkers as a final solution. You can try our AI Plagiarism Checker for free.’

What Is The Best AI Plagiarism Checker Free?

The best free tool to detect AI-generated text and/or plagiarism depends on your personal, organizational, or entrepreneurial needs.

Based on our research, these five tools here are absolutely free to use:

  • Undetectable AI
  • Copyscape
  • GPTZero
  • GLTR
  • Originality AI

We recommend starting with Undetectable.ai to identify AI-generated text, as it shines with its user-friendliness and affordability. The AI plagiarism detection can be done for absolutely free.

Is using ChatGPT plagiarism?

As of February 2024, the answer is maybe. ChatGPT may be ‘accidental plagiarism.’

ChatGPT has been pre-trained on over 40 terabytes of text. This is close to 40 million books. While you may create content that is so different from the original that it can’t be traced back to it – ChatGPT undoubtedly contains a large amount of original work.

We strongly recommend using an AI-detection model, such as Undetectable AI, to avoid plagiarism – or any future claims of plagiarism.

You can try Undetectable AI easily with the widget below (English only). Simply paste your text and see how quickly it can detect AI-generated content.

Try it for FREE today and ensure academic integrity in your institution.

Rated #1 AI Detector by Forbes

Disclaimer: Undetectable.ai is our solution. We’ve done our best to present the information evenly because we want you to make an educated decision. That said, we are proud of our software and built it with the AI plagiarism features and ease of use that we’d want. Scan a text for AI plagiarism here.

Undetectable AI (TM)