BTD File

What are BTD files and how to open them

Are you having problems opening a BTD 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 BTD files.

What is a BTD file?

BTD files have multiple uses, and BREAKTHRU Song is one of them. Read more about the other uses further down the page.

BREAKTHRU Song

BREAKTHRU Song files store complete song projects created by the Breakthru sequencer by Gajits Music Software on the Atari ST family of computers. These files encapsulate both MIDI-based and sample-based track data, instrument settings, tempo maps, cue sheets, sample palettes, mixing controls (volume, pan, bank, program numbers) and arrangement layout for full song playback and editing.

Files are produced by the Breakthru program when saving a song project file. Users can later reload these files into Breakthru to resume work: editing individual tracks in step or real-time modes, arranging song structure via cues, replaying or adjusting samples, or exporting via MIDI. Breakthru supports up to 64 tracks, simultaneous MIDI and sample data, 8-bit or 16-bit samples, and includes a sample palette so that the file often references external or embedded samples depending upon save options.

Files begin with a signature of four bytes reading Dsng at the very start, followed by metadata that allows identification of this format (for example the presence of the words PLUS and THRU in its contents). These internal markers help distinguish genuine Breakthru Song files from other data.

How to open BTD files

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

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

Last updated: August 25, 2026

All known file formats using extension .BTD

While BREAKTHRU Song is a popular type of BTD-file, we know of 2 different uses of the .BTD file extension. Different software may use files with the same extension for different types of data.

Power To-Do List Data

Power To-Do List Data files hold the task-management data used internally by the Swift To-Do List application on Microsoft Windows. They store everything the program needs to remember about to-do items, notes, reminders, task completion status, scheduling, attachments, and related metadata for all your to-do lists.

Swift To-Do List both writes and reads these files whenever tasks are added, edited, deleted or when the program starts; users typically interact with tasks through the Swift To-Do List interface, not by opening these files directly. No publicly documented converter exists to export these files to other formats by structure; the program provides its own export features for readable formats.

Files of this format begin with a distinctive sequence of bytes used as a signature: the first eight bytes are 43 61 C9 43 62 CD BD 3F (ASCII roughly "Ca.Cb..?") at offset 0, and another known signature is B5 75 95 44 6D DC 47 at offset 96.

Various apps that use files with this extension

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

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 BTD file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.