Censys vs UK Police

Censys grew out of the University of Michigan's ZMap internet-scanning research and now re-scans the full public IPv4 space multiple times a day, fingerprinting open ports, services, and TLS certificates. Its Search API exposes that host and certificate-transparency dataset for asset discovery, exposure monitoring, and threat hunting, and underpins Censys's own attack-surface-management product. Access is account-scoped through an API key, with a limited free community tier and metered paid plans for higher query volume.

The UK Police API publishes crime, stop-and-search, and neighbourhood-policing data reported by the 43 territorial forces of England and Wales, going back to December 2010 for street-level crime. It's a keyless JSON REST API -- force listings, neighbourhood team info, individual crime and outcome records, geo-radius crime queries -- released under the Open Government Licence, so results can be reused (including commercially) with attribution. Anonymous requests are capped at 15 per second with a burst of 30 before a 429 kicks in, comfortably enough for the dashboards and research tools that already build on it.