Maintained by: NLnet Labs

About Unbound

Unbound is a validating, recursive, and caching DNS resolver.

The C implementation of Unbound is developed and maintained by NLnet Labs. It is based on ideas and algorithms taken from a java prototype developed by Verisign labs, Nominet, Kirei and

Unbound is designed as a set of modular components, so that also DNSSEC (secure DNS) validation and stub-resolvers (that do not run as a server, but are linked into an application) are easily possible.

The source code is under a BSD License.


The latest source code tarball is available for download.


Report bugs using bugzilla here.

Mailing List

You can subscribe to the unbound users mailing list here.

Browse the archives of unbound-users.

Maintenance and Support

Unbound is being maintained by NLnet Labs, a not for profit, public benefit foundation. Problems can be reported through the bugzilla webinterface. In the case we stop supporting the product we will announce such two years in advance.

Unbound is subject to NLnet Labs Security Patch Policy

Commercial support for Unbound is available from several organizations.

Code Repository

The repository for unbound is available at

The development tree is located in trunk/.

User Groups

The Japan Unbound Users Group () provides documentation and support in Japanese.


Release 1.7.3

Thu June 21 10:20:15 CEST 2018
Version 1.7.3 of unbound has been released.

Release 1.7.2

Thu June 11 10:20:15 CEST 2018
Version 1.7.2 of unbound has been released.

Release 1.7.1

Thu May 03 10:20:15 CEST 2018
Version 1.7.1 of unbound has been released.

Release 1.7.0

Thu Mar 15 10:20:15 CEST 2018
Version 1.7.0 of unbound has been released.

Release 1.6.8

Fri Jan 19 10:20:15 CEST 2018
Version 1.6.8 of unbound has been released.

Release 1.6.7

Tue Oct 10 11:20:15 CEST 2017
Version 1.6.7 of unbound has been released.