ABY File

What are ABY files and how to open them

Are you having problems opening an ABY file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ABY files.

What is an ABY file?

An .ABY file is an AOL Address Book file.

The AOL Address Book format with extension .aby is a proprietary data file created by AOL to store a user's contacts locally. It records an individual's address book entries - such as names and email addresses - for use by AOL's Desktop software when managing a user's online address book from the computer.

These .aby files are typically written automatically by AOL software and are used to synchronize or back up address book data so that contacts are available locally when offline or when restoring data. When using AOL Desktop, the program reads the .aby file to display and edit contacts; exporting of the data to other formats (CSV, vCard, etc.) may be possible through compatible tools or AOL's export functions.

Technical details include a file header that begins with the ASCII signature AOLDB-25 at byte offset 0 and followed by the ASCII string R2D2 at offset 25. These byte signatures help validate that the file is indeed an AOL Address Book file.

How to open ABY files

Important: Different programs may use files with the ABY file extension for different purposes, so unless you are sure which format your ABY file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 16, 2026

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