Bonjour is a zero-configuration networking method developed by Apple. The technology makes it possible for computers, mobile devices, and printers to find and connect to one another automatically using a communication protocol. Bonjour saves time and simplifies tasks such as file sharing and setting up network printers. The technology is based on Internet Protocol (IP), so it works with wired and wireless networks.
Information in this article applies to Macs running macOS Catalina (10.15) through OS X Lion (10.7), iPhones, iPads, Apple TVs, and Windows 7 through Windows 10. Bonjour technology is also installed in many printers.
Bonjour is not an independent application. It's a collection of networking technologies that is used by apps, computer operating systems, iOS mobile devices, and other products. It functions behind the scenes and is enabled on all Macs by default. For example, iTunes uses Bonjour to locate other computers that are running iTunes on your network to manage shared media libraries.
Capabilities of Bonjour
Bonjour technology manages network shared resources as types of services. It automatically discovers and keeps track of the locations of these resources on a network as they come online, go offline, or change IP addresses. It provides this information to network applications to give users access to the resources.
As an implementation of zero-configuration networking (zeroconf), Bonjour supports three key discovery technologies:Address assignment: Bonjour uses a link-local addressing scheme to automatically assign IP addresses to local clients without the need for Dynamic Host Configuration Protocol (DHCP). It works with IPv6 and legacy IP (IPv4) addressing schemes. On IPv4, Bonjour uses the 169.254.0.0 private network; it uses the default link-local addressing support in IPv6.Name resolution: Name resolution in Bonjour works via a combination of local hostname configuration and multicast DNS (mDNS). While the public internet Domain Name System (DNS) relies on external DNS servers, multicast DNS works within a local network and enables any Bonjour device on the network to receive and respond to queries.Location services: To provide location services to applications, Bonjour adds a layer of abstraction on top of mDNS to maintain browsable tables of Bonjour-enabled applications that are organized by service name.
Apple took special care with the implementation of Bonjour to ensure its network traffic did not consume an excessive amount of network bandwidth. In particular, the mDNS includes caching support that remembers recently requested resource information.
Bonjour Computer Support for Apple Products
The operating system and many apps on Mac desktop and laptop computers depend on Bonjour, which is installed and enabled by default on these devices. Bonjour also comes with Apple's iOS and iPadOS operating systems for its mobile devices and is part of every iPad, iPhone, iPod touch, and Apple TV.
Apple computers running versions of Mac OS X and macOS support Bonjour. It is embedded in network applications such as the Safari web browser, Music or iTunes, and iPhoto.
Macs require Bonjour to function properly. It should not be removed or disabled.
Bonjour Computer Support for PCs
Apple provides a Bonjour version for Microsoft Windows PCs as a free software download available for Windows 10, 8, and 7. It is included with iTunes software if you use it on your PC. It is particularly useful in a home where both Macs and PCs use the same printer and other devices.
Unlike Macs, Windows PCs do not require Bonjour to function correctly, although any app that installs it for its own use (like iTunes) may not work well without it. It is safe to remove Bonjour from PCs. You'll find it under Programs and Features in the Control Panel.
Businesses that run Windows PCs but not Macs (or software that requires Bonjour) don't need to install Bonjour. If PCs and Macs are on the same network, Bonjour is a helpful Windows installation.
How Applications Work With Bonjour
Usually, applications use Bonjour services through standard TCP/IP calls.
Several Bonjour Browser Creative Commons-licensed applications have been developed. The software for desktop and laptop computers, phone and tablet apps allow network administrators and hobbyists to browse information about Bonjour services that advertise themselves on active networks.
Bonjour technology offers a set of Application Programming Interfaces (APIs) for both macOS and iOS applications. Apple Developers can access additional information at Bonjour for Developers.