Copyscape is free, with of course a "catch" to make some money. Copyscape has a limit of scans per website, so if you want to scan for example: asktom.com then you can only scan it a certain amount of times per month, and that includes any pages within asktom.com (eg. asktom.com/page). So if you want to scan a number of pages on your website, then you're going to have to go premium.
But why go premium when there is a great free alternative online?
Plagiarisma comes with all the free features Copyscape gives for free, but Plagiarisma comes along with 2 or more extra features and of course the features are all unlimited unlike Copyscape.
So check it out, and don't forget to leave a comment below with your favourite plagiarism checker!
So check out: Plagiarisma