The Whois XML Reverse WHOIS API allows developers to find all domain names which contain a specified search term (i.e., name, email, address, phone, etc.) in their WHOIS records. Query results provide all the domain records that correspond to the search terms used and are made available in XML & JSON formats. With the API, it's possible to discover all domain names associated with an individual or an organization as well as find connections with other domains and their owners. Practical usages include cybersecurity, law enforcement, brand protection, marketing research, and cyber fraud prevention.