It is not related to open source software the service is based on closed-source software. The name 'OpenDNS' refers to the DNS concept that queries are accepted from any source. The services are based on software proprietary to the company.

Until June 2014, OpenDNS provided an ad-supported service and a paid advertisement-free service.

Cisco said that it intended to continue development of OpenDNS with its other cloud-based security products, and that it would continue its existing services. OpenDNS's business services were renamed Cisco Umbrella home products retained the OpenDNS name. On August 27, 2015, Cisco acquired OpenDNS for US$635 million in an all-cash transaction, plus retention-based incentives for OpenDNS. The OpenDNS Global Network processes an estimated 100 billion DNS queries daily from 85 million users through 25 data centers worldwide. OpenDNS is an American company providing Domain Name System (DNS) resolution services-with features such as phishing protection, optional content filtering, and DNS lookup in its DNS servers-and a cloud computing security product suite, Umbrella, designed to protect enterprise customers from malware, botnets, phishing, and targeted online attacks.

Opendns dnscrypt resolver