BLU File

What are BLU files and how to open them

Are you having problems opening a BLU 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 BLU files.

What is a BLU file?

A .BLU file is an Apple Binary 2 Library Utility Archive file.

Binary II Library Utility Archive files bundle together one or more Apple II files along with their file attributes (such as type, date, creator codes) in a single container. These archives are created by the Apple II program called BLU (Binary Library Utility), which runs under ProDOS or GS/OS and was written by Floyd Zink, Jr., to help with reliably transferring, storing, and organizing files for Apple II systems.

BLU lets users package many files (or even entire subdirectories), compress them with "Squeeze" compression, wrap them in a "Binary II" wrapper ("bunnying") that preserves filetype metadata, and then later extract, list, or manage those files. It includes menu options for cataloging disks, making Binary II files, squeezing and unsqueezing files, deleting or extracting files out of a Binary II archive, and listing contents. BLU version 2.28 automatically handles both squeeze and bunny steps together.

Files in this format begin with a Binary II file header; the first four bytes are 0A 47 4C 02 in hexadecimal (ASCII ".GL" followed by byte 0x02) at the very start (offset 0). That signature identifies files produced by BLU or Binary II utilities.

How to open BLU files

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

While we have not verified the apps ourselves yet, our users have suggested four different BLU openers which you will find listed below.

Last updated: August 24, 2026

Various apps that use files with this extension

These apps are known to open certain types of BLU files. Remember, different programs may use BLU files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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