ATTR File

What are ATTR files and how to open them

Are you having problems opening an ATTR 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 ATTR files.

What is an ATTR file?

An .ATTR file is an IPhoto Image Data file.

IPhoto Image Data (.ATTR) files store image-attribute metadata used by Apple's iPhoto software. They accompany individual photos in an iPhoto library, holding the edited attributes - captions, dates, original filenames, user-added labels, and other metadata that iPhoto uses to track information that is distinct from the image file itself.

These files are generated by iPhoto (versions 2 and earlier) when image metadata is altered, such as changing the caption, modifying the date, or adding user data. The metadata later helps iPhoto organize, sort, and display images in the library. In iPhoto 4 and later, these files are no longer used, though older libraries may still contain them.

On the technical side, these files are binary-serialized property lists in Apple's "typed stream" format. That internal structure includes Objective-C classes like NSDictionary, NSMutableDictionary, NSArray, NSString, NSNumber, NSDate, NSData, and NSObject. They often contain keywords such as AttributeMgr, Attributes, ImageUserData, OrigFilename, OrigArchiveFilename, Caption, ModificationDate, Since70Interval among others. Files begin with a signature showing "typedstream" and "AttributeMgr" near the start.

How to open ATTR files

Important: Different programs may use files with the ATTR file extension for different purposes, so unless you are sure which format your ATTR 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 22, 2026

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