Bonjour is a networking technology that lets you create an instant network of computers and devices without any configuration. It allows the services and capabilities of each device to be registered on the network, and allows these services to be dynamically discoverable by other devices on the network.

The open source mDNSResponder project contains the Bonjour service discovery implemenation that's built into Mac OS X and Bonjour for Windows. Additionally, this project contains the mDNSResponder daemon for POSIX and the Java libraries for all platforms. Hardware developers are encouraged to embed the mDNSResponder source code into their firmware.

The mDNSResponder daemon source code is licensed under the terms of the Apache License, Version 2.0. To accommodate compatibility with the widest possible range of client source code licenses, the DNS-SD shared library source code is licensed under the "Three-Clause BSD License".