.ABCDDB File

File extension abcddb is most likely best known for its use in Apple Address Book, an address book for Apple's Mac OS X computers with many syncing features that are integrated into rest of the OS.

A typical .abcddb file contains stored contact address book data in SQLite format.

Files with abcddb suffix are almost always contacts databases from Apple Address Book (Contacts) management software macOS / OS X.

How to open:

You can import these files to your Apple Adress Book. Exclusive format for Mac platform.

How to convert:

You can find utilities on App Store that allows users to export contacts from ABCDDB files to several formats, including CSV or VCF.