Dupli Checker is one of the most comprehensive plagiarism checker and writing assistant tools that you can use to write error-free content. The site offers a number of other useful tools such as grammar checker, spelling checker, text to speech, image to text, and more.
You can use all those tools for free. Dupli Checker offers premium plans as well if you need more options and features, you can sign up for a premium plan as well.
If you go for the premium plan, you can do a plagiarism check upto 10,000 words and a much deeper search to make sure that your content is completely unique.
The Dupli Checker plagiarism checker tool is simple and easy to use, all you have to do is to paste your content and make a search, the system will search through all possible sources and give you the results.
You can also check your content through the URL of a page as well as you can upload a document with your content (.tex, .txt, .doc, .docx, .odt, .pdf, .rtf formats are supported)