AFF4 File

What are AFF4 files and how to open them

Are you having problems opening an AFF4 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 AFF4 files.

What is an AFF4 file?

An .AFF4 file is an Advanced Forensic Format 4 Disk Image file.

Advanced Forensic Format 4 Disk Image is an open, object-oriented forensic evidence container designed for capturing, storing, and analyzing disk-images and other digital evidence in investigations. AFF4 separates the data (evidence content) from metadata (information about the evidence), supports multiple types of evidence in a single container, and enables efficient handling of large datasets through chunked and indexed segments. AFF4 supports compression (e.g. zlib) and may include cryptographic metadata for verification and signing.

Entire disk, memory, network packet, extracted logical files, and metadata can all be stored within AFF4. The format uses named objects identified by globally unique URNs; image data are divided into compressed chunks collected into units called bevies, with indexes to allow random access. AFF4 containers are implemented as directory-based volumes or ZIP/ZIP64 archives; metadata is often stored in RDF/Turtle files such as information.turtle.

A technical signature of an AFF4 file is that its container begins with the ZIP local file header signature "PK\x03\x04" at offset zero, as AFF4 uses the ZIP format for its volume. Within the archive, there are files such as information.turtle (RDF), version.txt, and named segments corresponding to image streams, map streams, or resources. AFF4 uses keywords and field names like aff4:ImageStream, aff4:Map, URN identifiers, and terms such as bevy and bevy index to describe its internal structure.

How to open AFF4 files

Important: Different programs may use files with the AFF4 file extension for different purposes, so unless you are sure which format your AFF4 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 17, 2026

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