Copyscape also let you submit up to 10 urls for free every month. But this chance is slim especially when the website has a lot of user. However, Copyscape charges very low fee. Check it's list of payment.
I have used copyscpae as well and I think it's a great service. Only $5 for 100 searches is nothing and gives a piece of mind that your content is unique. It really helps a lot when you buy articles from writers that claim it is unique because you can quickly weed out the bed ones from the honest ones. Recommended for the price.
Copyscape is only free for the first ten uses per month. Recently I've been using http://searchmaze.com/plagiarism.html which does the same thing for free. Use copyscape for your first 10 searches, and use search maze for the remainder.
I just tried Searchmaze and it came back with "nothing found" even on the bits I copied directly from a website and put in the search box. I tried using each search engine individually and all four together and it came back with the same "nothing found" results.
Are you sure Searchmaze is accurate on finding plagiarism the way Copyscape does?
