Shodan is described as 'Search engine that lets you find specific computers (routers, servers, etc.) using a variety of filters. Some have also described it as a public port scan directory or a search engine of banners' and is an app in the network & admin category. There are more than 25 alternatives to Shodan for a variety of platforms, including Web-based, Linux, Windows, SaaS and Mac apps. The best Shodan alternative is Criminal IP, which is free. Other great apps like Shodan are ZoomEye, Censys, IVRE and FOFA.