competitors top referring sites

We need a system that can crawl the web for all reffering domains/urls to a website, just like these services present the information: alexa majesticseo [login to view URL] etc. As the site only will be used as an internal tool, focus should only be on the backend, and a simple page to present the results. Eg. I enter [login to view URL] And the service will provide a list of all referring domains/urls Only developers who has experience in working with spiders/web crawlers will be taken into consideration. Please send references on similar projects/tasks. Thanks