BSQ File

What are BSQ files and how to open them

Are you having problems opening a BSQ 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 BSQ files.

What is a BSQ file?

A .BSQ file is a BSQ Encoded Data file.

BSQ Encoded Data is an Apple II-era transfer encoding created by the BinSCII program to safely send binary files over text-only channels. It wraps a binary file inside an ASCII-text container that includes filename and metadata so that the correct Apple II filetype can be restored after decoding. The encoding was commonly used on bulletin-board systems and Usenet in the 1980s and 1990s to ship ProDOS files, archives such as ShrinkIt/NuFX, or other binary data. Once decoded with a matching BinSCII-compatible program, the resulting file is then passed to any required decompression or unpacking tool.

The encoding is entirely in plain text except for special control characters and checksum/segment data embedded in its lines. Headers mark the start of the encoded contents, and the body encodes bytes using a restricted printable character set. Every segment of the encoded file identifies itself and records its part number so segments can be reassembled in any order. The encoding includes a footer to verify integrity after transfer.

Files of this kind begin with the ASCII signature "===BSQ1FILE" at offset zero, signaling version 1 of this BinSCII-based BSQ encoded data. This header identifies the encoding version and that the file contains wrapped binary data awaiting decoding back into its original binary form.

How to open BSQ files

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

While we have not verified the app ourselves yet, our users have suggested a single BSQ opener which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of BSQ files. Remember, different programs may use BSQ 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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