Files with abbu extension can be often on macOS / Mac OS X as address book archives for Apple Address Book (Contacts).
Software that open abbu file
ABBU file extension - Apple Address Book contacts archive
What is abbu file? How to open abbu files?
File extension abbu is best know for its use in Apple Address Book application used to manage addresses and other contacts information.
The .abbu file contains archived contact information exported from the Address Book database. From Mac OS X Mountain Lion The Address Book is renamed to Contacts.
The default software associated to open abbu file:
Address Book (Contacts) for Mac 
Company or developer:
Apple, Inc.
The Address Book (Contacts) is a little handy application with loads of features that are often overlooked by most users. Its very useful for for organizing your contacts, but Address Book's real power is that it works with many other applications. Its an integral part of Mac OS X (macOS) operation system. From Mac OS X Mountain Lion the Address Book will be renamed to Contacts.
Company or developer:
Apple, Inc.
OS X or Mac OS X is Unix-based operating system developed by Apple Inc. for Macintosh computers. It contains basic core applications for everyday use, such as Finder basic file manager, Safari for Internet browsing, QuickTime for video, iTunes for managing audio data and iPod, iOS devices management , iMessage instant messaging, Mail, Contacts, Calendar and many more.
The latest version 10.11 of OS X is called El Capitan. It is available to purchase on Mac App Store as well as is distributed with new Mac computers and notebooks. It includes features to improve the security, performance, design and usability.
OS X operating system was replaced by new macOS in 2016!
Company or developer:
Apple, Inc.
macOS is Unix-based desktop operating system, a successor of Mac OS X system for MacBook-family, iMac, Mac Mini and Mac Pro computers, developed and sold by Apple, Inc.
List of software applications associated to the .abbu file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open abbu file, edit abbu file, convert abbu file, view abbu file, play abbu file etc. (if exist software for corresponding action in File-Extensions.org's database).
Hint:
Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting abbu files.
Software that open abbu file - Apple Address Book contacts archive
Programs supporting the exension abbu on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about Address Book (Contacts) for Mac for open abbu file action.
