Unbound is a validating, recursive, and caching DNS resolver product from NLnet Labs. It is distributed free of charge in open-source form under the BSD license.

Unbound runs on all Linux and BSD distributions, as well as macOS, with packages available for most platforms. It is included in the base-system of all major BSD operating systems and in the standard repositories of most Linux distributions. Installation and configuration is designed to be easy. Setting up a resolver for your machine or network can be done with only a few lines of configuration.

It is free, open source software under the BSD license. The guiding principles for our product development roadmap are first and foremost the security and privacy of the user. In addition, all functionality must be backed by well established open standards. We continually improve the functionality of Unbound for all of our users. This means we do not make custom builds or provide specific features to paying customers only. Our priorities are guided by the feedback of our user base, in particular those users with a support contract, as well as the wider Internet community. Sponsored functionality will be given a higher priority where possible and is evaluated on a case-by-case basis.

Find out more here.