
DNS, WHOIS/RDAP, SSL, subdomain enumeration, and email security in one parallel call.
Domain Intelligence API is a free Security API that requires apiKey authentication, is served over HTTPS and does not support CORS, so it should be called from a server.
Free WHOIS API, DNS lookup, SSL inspection, subdomain enumeration & email security in one call. 1,000 free requests/mo, no credit card.
Details from oti-labs.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Ephemeral zero-knowledge encrypted data sharing
The Domain Intelligence API is provided by Osiris Technical Institute (oti-labs.com). Free WHOIS API, DNS lookup, SSL inspection, subdomain enumeration & email security in one call. 1,000 free requests/mo, no credit card.
Yes. The Domain Intelligence API is listed in the Security category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The Domain Intelligence API uses apiKey authentication, so you need to register for credentials before making requests.
Not directly. The Domain Intelligence API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The Domain Intelligence API is served over HTTPS, so it's safe to use in production.