Shodan

Shodan is a search engine that indexes devices connected to the internet rather than web pages. Its crawlers collect service banners and open-port information from servers, routers, cameras, industrial systems and many other devices, and users can search that data to see what is exposed and who runs which technology.

The platform includes search, maps and images views, a Monitor product that watches a network range and sends real-time notifications when something unexpected appears, and a developer API for IP lookups, searching and data streaming. Browser integrations show a quick security view of the site being visited. The vendor says it crawls the internet on a weekly cycle.

Shodan is a hosted commercial service with public sign-up, and it cannot be self-hosted. It is commonly used by security researchers, defenders and network administrators for attack surface checks, and by analysts studying technology adoption.