BBT File

What are BBT files and how to open them

Are you having problems opening a BBT 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 BBT files.

What is a BBT file?

A .BBT file is a BackBit Tool Format file.

BackBit Tool format stores programs and disk images plus optional extras for use with the BackBit cartridge for the Commodore 64, enabling combined usage scenarios and extended data access. It is created by the BackBit Tool software written by Evie Salomon and allows packaging game or software content along with startup routines, disk images, and binary data so that the cartridge firmware can present them to the C64 as disk or program files.

Files in this format are assembled by BackBit Tool, which accepts an optional auto-start program (a PRG), up to eight disk image files (D64, D71, D81, or a combined format called D8B), and one block of "extended data" - an extra binary file up to about 4 GB. The BackBit Tool tags important metadata like title text and screenshots, embeds a title screen or SID music, and aligns all fields on 16-byte offsets so that the cartridge firmware can interpret them correctly.

Technical signatures include an ASCII header "BACKBIT" at the very start of the file and the presence of the string "BACKBITSBACK" somewhere within the file.

How to open BBT files

Important: Different programs may use files with the BBT file extension for different purposes, so unless you are sure which format your BBT 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 BBT openers which you will find listed below.

Last updated: August 23, 2026

Various apps that use files with this extension

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