I do not want to insert the contents of the blog on some dodgy website. Is there a site that you trust that is reliable for a plagiarism check? 
One popular choice is Turnitin. It’s widely used by educators and professionals alike for its accuracy and credibility. Plus, it offers detailed reports to help you understand any similarities found in your content.
Another trustworthy option is Grammarly. While it’s known primarily as a grammar checker, its plagiarism detection feature is top-notch. It scans your text against a vast database to ensure originality.
And if you’re looking for a free option, you can’t go wrong with Copyscape. It’s been around for a while and is known for its reliability in detecting duplicate content across the web.
I am also on the lookout for free options but have not found any yet. If you come across any, let me know. I’ve heard about paraphraser.io but I am not sure if it is any good.