Nomulus is an open source, scalable, cloud-based service for operating top-level domains (TLDs). It is the authoritative source for the TLDs that it runs, meaning that it is responsible for tracking domain name ownership and handling registrations, renewals, availability checks, and WHOIS requests. End-user registrants (i.e. people or companies that want to register a domain name) use an intermediate domain name registrar acting on their behalf to interact with the registry.Nomulus runs on Google App Engine and is written primarily in Java. It is the software that Google Registry uses to operate TLDs such as .GOOGLE, .HOW, .SOY, and .みんな. It can run any number of TLDs in a single shared registry system using horizontal scaling. Its source code is publicly available in this repository under the Apache 2.0 free and open source license.