Duplicate content can hurt your search engine rankings very badly so it’s your duty to find and fix duplicate content issues. There are many online tools which you can use to find duplicate content online for free.
I have found the top 10 websites which you can use to identify duplicate content, the top 10 duplicate content checkers is below so check them out and let me know what do you think.
Note: I only like copyscape.com because I trust this tool and this ones shows very accurate results than any other tool, but there is a dis-advantage which is you can’t scan more than 8 urls per month.
10 Duplicate Content Checkers List
10. Article Checker