https://nocramming.com/plagiarism-checker is actually a decent free AI plagiarism checker as mentioned earlier. Can say that it’s the only one I use, and some of my professors use it too. I don’t see the point in paying for paid AI checkers.
If you need someone to do my project for me, I’d say avoid the super cheap “instant delivery” websites.
I used one before and half the content looked generic. Later I switched to PaperWriter for a research-heavy assignment and the quality was much better. More expensive, yes, but at least usable.