Duplichecker Review: Still the best content plagiarism detector in 2024?

This article has been updated for 2024. 11 years have passed since we first reviewed Duplichecker in 2013. The tool has changed since then. Is it still good?

First things first, Duplichecker is no longer just a plagiarism detector – it’s also an AI content detector, so not only can it tell you if your writing has been plagiarised, it’ll also tell you if ChatGPT or some other AI tools have written it.

Hoorah!

Duplichecker, you say?

Yes, and you can check it out at https://www.duplichecker.com/.

Duplichecker is an online content plagiarism detector with copy and paste and URL functionality. Less well known than Copyscape, Duplichecker offers the ability to check content for plagiarism through copy and paste or by uploading a .doc or .txt file.

Here’s what the plagiarism tool looks like:

You can upload 1,000 words of content per search, making it ideal for checking articles that you have had written for your business.

Duplichecker features

• 100% free.
• 1,000 words per search.
• Copy and paste.
• Check Plagiarism via webpage URL.
• .tex, .txt, .doc, .docx, .odt, .pdf, .rtf file upload.
• URL check.
• 100% detection rate, 95% quote success rate (in our tests conducted in 2024).

Duplichecker Pro features

• No ads.
• Check Plagiarism via webpage URL.
• 25,000 words per search.
• Customer support and help.

What’s it like?

Duplichecker is one of many content plagiarism detectors available online.

100% free to use, Duplichecker sets itself apart from the competition by offering the ability to instantly upload text in a variety of formats.

Compared to Copyscape and Plagspotter, Duplichecker returns a good rate of plagiarism detection.

Duplichecker is so simple to use that anybody can use it. Content marketers, content writing agencies, business owners, students; no matter who you are Duplichecker is accessible for all.

Ahh, but I bet it costs money down the line?

Nope, not a penny. It’s free unless you plump up for the Pro version.

Does it work?

Yes, it does, with a 95% to 100% success rate.

In order to test the plagiarism detection rate in Duplichecker, we carried out two tests a total of 15 times each.

First we copied a 100-word paragraph of text from a Google and Bing indexed article and pasted it into a unique 1,400-word article. We then uploaded the text to Duplichecker and pressed submit.

The second test involved copying just 40 words of text and pasting it into a 1,460-word article.

The result?

Duplichecker passed with a result of 100%, pointing us directly to the very web page from which we copied the text, and it also highlighted lesser sources who either quoted or copied text themselves.

This was an astounding result and proof that the tool can be trusted by marketers.

We did find that Duplichecker’s detection rate fell to 40% when just 20 words were uploaded, however, we never expected the tool to be able to detect that low level of plagiarism.

95% success rate for quotes

Duplichecker handles quotes with a 95% success rate.

The 5% miss rate came about when we used very short quotes.

For example, the quote “Problems are not stop signs, they are guidelines” pasted into a unique 900-word article returned two results. This quote from Robert H. Schuller is used in thousands of articles online. We had the same results with another 3 quotes.

Does this matter? Not really.

You see, quotes are quotes. It’s impossible to plagiarise a quote because it is impossible to use a quote without writing it word for word.

If you do use quotes in your content, link to the source. And if it’s a famous saying, don’t sweat it.

Duplichecker Pro

Duplichecker Pro costs between $10 and $20 per month. For that, you get:

• 25,000 word count boost.
• Real-time global web crawling (meaning it searches the web now, not a cached version).
• Versatile file format support for seamless integration.
• Customisable PDF reports for convenient portability.
• State-of-the-art plagiarism detection algorithms.
• Content rephrasing functionality (English language only).
• URL validation and analysis.
• 99.9% operational uptime.

Duplichecker AI Detector

Duplichecker’s AI detector can help you figure out if a given piece of text has been generated by an AI or written by a human. Here are the key features and capabilities of this AI Detector tool:

1. Free to use with no sign-up required. Users can simply paste or upload their text content directly on the website.
2. Uses ‘advanced natural language processing’ (NLP) and machine learning techniques to analyse the submitted text – an ambiguous description that means little.
3. It provides a percentage score indicating how much of the text is likely to be AI-written versus human-written.
4. It can detect text generated by popular AI models like GPT-3 and GPT-4 (ChatGPT).
5. It claims 100% accuracy in detecting AI-generated text using its advanced algorithms.

So, is it any good?

It detected 100% of the GPT-3 and GPT-4 text we inputted with a range between 95-98% AI.

Editing some of the phrases and sentence structures of AI-generated text can drop the tool’s AI score down to between 80% and 90%.

ChatGPT text requires heavy editing and syntax changes to pass Duplichecker’s AI detection tool – making it a decent option for quality control.

However, Duplichecker is no good at catching out Claude. We asked Claude a simple question, ‘What is SEO?’, and it said:

SEO stands for “Search Engine Optimization.” It is the practice of optimizing websites and web pages to rank higher in search engine results pages (SERPs), like Google, Bing, or Yahoo.

The main goal of SEO is to improve a website’s visibility and organic (non-paid) search traffic from search engines. This is achieved by implementing various strategies and techniques that help search engines understand the content and structure of a website better, making it more likely to rank higher for relevant search queries.

Claude

Duplichecker says this text is 100% human written.

Oops.

The bottom line? Duplichecker’s AI detection tool is not reliable if you intend to use anything but GPT. A more reliable option is GPT Zero.

But what about Copyscape?

Copyscape is the number one content plagiarism detector online. However, in order to be granted the ability to upload text, you need to sign up to Copyscape Premium, a paid service (it costs 3 cents per search in USD). This is expensive when Duplichecker is free.

At Content Hero, we have signed up to Copyscape, but we use Duplichecker more for copy and pasting because it is free and it offers the exact same results.

Overall

As a free tool, Duplichecker is a valuable resource. Our own tests have found that it offers as good a detection rate as Copyscape Premium and that alone is a good enough reason to use it.

That said, Duplichecker is not the be-all and end-all of plagiarism detection. As a content marketer, utilising all available resources close to you is recommended.

Other top services include Plagspotter and Grammarly — Grammarly also has a decent grammar editor, but beware of the AI content feature, which always gets caught out by AI detection tools and defeats the point of original writing.