BLOB File

What are BLOB files and how to open them

Are you having problems opening a BLOB 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 BLOB files.

What is a BLOB file?

BLOB files have multiple uses, and Android Assembly Store is one of them. Read more about the other uses further down the page.

Android Assembly Store

Android Assembly Store files are special structured binary blobs used by .NET for Android to package together all managed assemblies (plus optional debug and configuration files) into a single store instead of including many separate DLLs. These stores are created during app building and are included inside the APK or AAB archive for use by the runtime. This packaging improves startup performance by minimizing file lookups and memory mappings.

Each build architecture supported by the app gets exactly one such store which is placed under lib/ABI/ in the APK or AAB, often wrapped inside a shared library so that the runtime can load or map the store efficiently. During execution the runtime locates the appropriate store for the current device architecture and maps it into memory to serve assembly load requests.

As a binary format the store begins with a fixed header including fields for magic number, version, counts of entries, index size, and a content hash. Following the header are five major sections: an index for assembly name lookups; a table of descriptors pointing to each assembly's data (and optionally debug or config data); a list of assembly names; and then the raw assembly image data (and any debug or config data). The header starts with the ASCII signature "XABA" (bytes 0x58414241) at offset zero.

How to open BLOB files

Important: Different programs may use files with the BLOB file extension for different purposes, so unless you are sure which format your BLOB 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 24, 2026

All known file formats using extension .BLOB

While Android Assembly Store is a popular type of BLOB-file, we know of 3 different uses of the .BLOB file extension. Different software may use files with the same extension for different types of data.

Cosmic Blobs model

These BLOB files contain the 3D animated models created in Cosmic Blobs. This software is designed for kids to develop, sculpt, and decorate 3D animated models known as Blobs. Blobs act as virtual clay for the computer, and it enables you to create cartoons and movies on your PC.

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!

Steam Registry

We know that one BLOB format is Steam Registry. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

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!

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about BLOB file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.