you could use Duplichecker tool, which is a online tool, it'll give you the source of plagarism too; if any. But it allows you to search 1000 words at at time, so you might need to perform multiple searches.

Plagiarism check is highly essential for all content writers, digital writers, social media writers, editors and even students, professionals and researchers. Based on my experience, I highly recommended (check its website: https://www.oxphrase.com/ ), which helps detect plagiarism and avoid inadvertent plagiarism in your writing. it is very accurate and reliable!

Dear Dr Kunal . , Turnitin is most widely used. Beside of Turnitin, you may follow other online plagiarism checker, but frankly telling I do not trust those online links when it comes to confidentiality of the materials. So, please think before you submit your materials to online platforms.

no safety of your document on online checking

You can use Turnitin plagiatism checker software to detect plagiarism.