Best plagiarism checkers - tested with non-original content

In the SEO world, you will often need to check content for plagiarism.

Either it’s a content you ordered from freelancers or someone is pitching you a guest post.

Non-original scraped content just won’t rank in Google.

Moreover, if you have a lot of stolen content, it’s a definite “low quality” sign for the whole site, so forget about any Google traffic. What even worse, your site can get penalised.

I collected top plagiarism checker tools and experimented with the same piece of content from my site.

Let’s see the results of each tool.

I’ve inserted nicely paraphrased piece of ~650 words, with one clearly stolen element.

Also, during check, I didn’t exclude my original source.


1. Copyscape

Often Copyscape is an industry standard.

Copyscape original content

It found 6 sources, 2 of which are my original articles.

From remaining four, 3 are Pinterest sites and one blog.


2. SmallSEOtools Plagiarism Checker

For the same content piece, I’ve got 100% unique content in SmallSEOtools Plagiarism Checker.

SmallSEOtools plagiarism checker

And even part, which is clearly non-original, was shown as unique.

Small SEO tools checker


3. Quetext

Quetext only shows two original sources from my site, similar to Copyscape.



4. Duplichecker

No plagiarism detected, 100% original content. 😅



5. EduBirdie


It identified 47.9% text uniqueness, with 8 sources of content (which is quite close to reality).

So, far it’s the best result.



100% original content


7. Unicheck

0% original content (because of one source from my site) and 17 sources.

But, the free check was only limited to 200 words.



8. Plagscan

82% non-original content. From 3 sources: my site and two Quora answers.


9. Prepostseo

100% unique content.


10. PapersOwl

53.3% non-original content, from 9 sources.

Pretty good.



Maybe, this is not the best reliable tool, from a .ru domain, but it showed an incredibly detailed result.

It found 10 sources for a non-original piece of content.

Sometimes, this tool is over-detailed and shows some content, which is, in fact, original, but just has some similar structure.

If you are a plagiarism junkie, this is your tool.


Plagiarism checker tools review

Therefore, according to this very simple and non-ideal research, Unicheck provided the most detailed and closest to reality plagiarism check.

Edubirdie, PapersOwl, Content-watch – also demonstrated quite good results.

More well-known tools, such as Copyscape, SmallSEOtools – were not that precise.



Best paid plagiarism checker tool: Unicheck

Best free plagiarism check software: EduBirdie


If I missed some great plagiarism tool or Chrome extension, hint a suggestion in comments.