What’s duplicate content? Identical content to other websites. And Google penalizes websites with it. Siteliner is an SEO checker tool that helps you find duplicate content on your website. You’ll be able to scan your entire website to find duplicate content, broken links, average page size and speed, the number of internal links per page, and more. It also compares your website to the average of websites checked with this tool to help you better understand where you stand.