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The best free online plagiarism checker

6 min read | Last updated on

Most of us likely think of plagiarism as happening within the educational system — think plagiarised student essays. However, plagiarism can happen in any situation in which content of any type is being created. And, since plagiarism kills credibility, it’s in your best interests to ensure you’re not publishing plagiarised content. The question is, do you have to invest in an expensive paid tool for that? Or can you use a free online plagiarism checker? Here’s what you need to know.

What is plagiarism?

Plagiarism is a type of fraud where someone passes off another person’s intellectual property (IP) as their own. Many think of it as applying to written work only, but it applies to any IP. The well known Obama Hope poster is a good example, where street artist, Shepard Fairey, used a photo of then President Obama as the basis of a painting and was accused of plagiarism (in fact plagiarism is such a tricky issue that the case was never resolved).

A criminal plagiarising by stealing someone’s ideas
A criminal plagiarising by stealing someone’s ideas

Why do you need to be concerned by plagiarism?

Plagiarism is a serious problem for business owners. As an example, if you own a business, you likely own a company website, which is an important tool to enable you to interact and conduct business with customers. Various types of content must be continually generated for your website, such as product and service descriptions, blog posts, articles, FAQs, and more. The presence of plagiarism in any content you place on your website undermines your credibility and can interfere with your search engine rankings. Plagiarized content can damage your reputation as an honest, trustworthy business and that can have repercussions such as loss of current customers, the inability to bring in new customers, and an overall reduction in sales. And it can be very hard to reverse that damage.

While plagiarism can be accidental, most often it’s done intentionally. For example, there are plenty of cheap, unscrupulous writers out there who will create content for you, representing it as their own unique work, but, unbeknownst to you, it’s actually been copied from existing work.

And the thing is, if you pay external content writers to deliver content to you, you’re still responsible for the uniqueness of that content. You must ensure it’s free from plagiarized material before it’s published on your website.

Eliminating plagiarism from your content

The internet is an almost limitless, instantaneous source of potential plagiarism, with millions of pages of content freely available and more being created every second. Because of this, you’ll have to be diligent if you’re going to detect and eliminate plagiarism from your website content.

If you’re not writing your own content, a great way of ensuring your content is free of plagiarism is to check it with a dedicated plagiarism checker.

A plagiarism checker is a sophisticated software program that works by using advanced database software to scan for matches between your text and pre-existing text. Perhaps due to the prevalence of plagiarism today, a wide variety of plagiarism checkers are currently available online, and there are both free and paid checkers.

The quality of the results can vary widely depending on the amount of content within the checker’s database as well as the algorithms used to determine whether something is indeed plagiarism. For example, some plagiarism checkers will only check for exactly replicated text (this is common among free online plagiarism checkers) while others will also check for content that’s been paraphrased. The latter is typically only available in paid tools.

Similarly, free tools typically only check text that’s publicly available on the internet. Paid tools typically include checks against all content that’s previously been entered into their systems and often include other paywalled content such as journal articles.

While plagiarism checkers are powered by sophisticated software and use advanced databases, they’re constantly evolving because no plagiarism checker can perfectly detect every instance of plagiarism in a particular piece of text. And, since these tools work by checking for similarities between pieces of text, not everything that gets flagged actually constitutes plagiarism. For example, common sayings aren’t plagiarism, but they may be flagged by lower-quality plagiarism defectors. So, while plagiarism is never acceptable, sometimes it’s ok to use content that’s been flagged as unoriginal content by a plagiarism check.

With this in mind, it is generally acceptable to allow plagiarism percentages in your content as follows:

  • Greater than 10% plagiarism is problematic. You should investigate all the flags and the majority of affected phrases should be re-written or displayed as fully-referenced quotes.
  • 5% to 10% plagiarism is not necessarily problematic but bears further investigation. It is advisable that you investigate all flagged content and re-write (or reference) phrases as needed.
  • 5% or lower may be acceptable, but should still be investigated to ensure all flagged phrases are not actual plagiarism.

While a free online plagiarism check may not be as robust as higher-quality paid alternatives, it’s certainly better than not doing any kind of checking and offers a quick and easy way to help identify and eliminate plagiarism from your website content (or indeed any other written content).

The best free plagiarism checker

So with the many free plagiarism checkers available, which is the best choice?

Check Plagiarism is a great free plagiarism checker. It offers the same basic features as most other plagiarism checkers and some additional ones that aren’t available in all plagiarism checkers, such as a paraphrasing tool and grammar checker. What sets this tool apart in my mind is its usefulness if you’re frequently checking long-form text like blog posts. While most free plagiarism tools will enable you to check up to 1000 words at a time, Check Plagiarism can scan up to 15,000 words for free and up to five .doc, .docx, .txt, or .pdf files in a single run.

So, should you use a free plagiarism checker?

If you’re writing your own content, running it through a free plagiarism check offers a good ‘just in case’ check for accidental plagiarism. If you’re paying decent rates to commission written content, a free plagiarism check is probably also sufficient for your needs. If, however, you’re paying low fees for content, there’s a higher risk that you’re being delivered plagiarised content, so I strongly recommend you invest in a high-quality paid plagiarism checker (or invest in higher-quality writers).


Dr Kelly Wade

Hi! I’m a full-funnel marketing specialist and my mission is to build a better tomorrow by helping organisations that solve crucial problems, efficiently generate sustainable growth with strategic marketing assets that attract, nurture, convert and retain the target market.

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