Security — entry 004 of 30
Censys
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.
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<a href="https://greatapis.com/api/censys/"><img src="https://greatapis.com/badge/censys.svg" alt="Scored 61 on greatapis.com"></a>Auth quickstart
- Get a key at the provider
- Send it on every request as a header
Authorization: <key> - The exact header isn't documented — Authorization is a common default; confirm in the provider's docs.
Your key is stored only in this browser (localStorage) and sent directly to the API — never to greatapis.
Developer reference
Concurrent Actions cap by account tier: Free 1, Starter 1, Search and Core 25 (usage is credit-metered per call rather than a pure per-window request count); Censys's own community team has confirmed no separate requests-per-minute/hour/day limit exists beyond this concurrency cap, per docs.censys.com/reference/get-started and community.censys.com/censys-platform-q-a-58/rate-limits-about-censys-platform-api-537.