Unbound is a validating, recursive, caching DNS resolver. It is designed to be fast and lean and incorporates modern features based on open standards.

To help increase online privacy, Unbound supports DNS-over-TLS and DNS-over-HTTPS which allows clients to encrypt their communication. In addition, it supports various modern standards that limit the amount of data exchanged with authoritative servers. These standards do not only improve privacy but also help making the DNS more robust. The most important are Query Name Minimisation, the Aggressive Use of DNSSEC-Validated Cache and support for authority zones, which can be used to load a copy of the root zone.