Develop a Web App that compares scraped data

Hi , I need a web app that will work as a comparison website. I need it to scrape data from a few websites (3,4 maybe more) and then present the results in a tabular form. The web app should be scalable so use ruby on rails or something similar. Please message for more details. Also please tell me the pros and cons of the framework you plan to use for this. Thanks in advance, Regards