FreeSitesLike - FreeSitesLike is a user contributed website dedicated to offering its visitors with plenty of options to a specific website.
AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.
SimilarSites - Easily find more sites like those you like.
SitesLikeSearch - SitesLikeSearch is one of the greatest sources over the internet dedicated to providing the list of those websites the similar or alternatives of which the users are looking for.
Product Hunt - A website that lets users share and discover new products
Similar Site Search - SimilarSiteSearch helps you find similar, related, or alternative websites.