Binary Edge
BinaryEdge continuously scans internet-facing devices and correlates the results so you can see your own attack surface — the ports, services, and exposures an outside attacker would find first. It sits in the same family as Shodan and Censys, and CISA lists it in its no-cost tools catalog (free tier: one user, limited monthly scans). Useful for external recon and for checking what your own infrastructure is quietly exposing to the public internet.