ACD File

What are ACD files and how to open them

Are you having problems opening an ACD 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 ACD files.

What is an ACD file?

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

ACID Pro Song

ACID Pro Song files are the native project files used by the ACID Pro digital audio workstation software (originally by Sonic Foundry, later Sony Creative Software, now developed by Magix). They store everything needed to build a multitrack audio composition except the actual recorded or looped sound clips themselves.

An .ACD file includes the number and layout of tracks, where each clip goes in time, which audio loops or recordings are referenced (but not the audio data itself), plus settings such as track volume, panning, envelopes, effects parameters, tempo, and any automation. Projects in progress use .ACD to save a song while relying on the source audio files stored elsewhere.

When working in ACID Pro, you create .ACD files via Save or Save As. To combine all referenced media into one archive, ACID offers a companion format - .ACD-ZIP - which embeds or copies all audio files along with the project file, useful for sharing or archiving.

On the technical side, .ACD files begin with a RIFF header ("riff......(…)" at offset zero), and internally contain tags and strings such as "A'C'D", "ACID", "MASTER", "BREAK", and metadata fields like INAM, ICMT, ICOP, IART, LIST, IENG, WBQE that help identify the format.

How to open ACD files

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

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

Last updated: August 16, 2026

All known file formats using extension .ACD

While ACID Pro Song is a popular type of ACD-file, we know of 6 different uses of the .ACD file extension. Different software may use files with the same extension for different types of data.

ACID Song

An ACID Song format (.ACD) is a project file used by ACID music software (originally from Sonic Foundry, later Sony and now Magix) to store everything about a music arrangement except most of the raw audio. It keeps track of how your song is built - which loops or recordings are placed on what tracks and when, what effects are applied, how loud each track is and where things pan in the stereo field, and other timing and editing information. It's the file you save while you're still working, not the exported final mix.

When the software writes an .ACD file it does not embed the full audio recordings in most cases; instead it stores links or references to the external media files you used (loops, WAV files, etc.). This lets you edit without altering your original recordings. The software reads the .ACD file and pulls in the referenced media to re-create the arrangement whenever you open the project. There is a variant called ".acd-zip" that does embed audio into the project file for archiving or easier sharing.

In technical terms the file begins with a RIFF header ("RIFF") then a chunk marked "ACIDfmt" among its first few bytes. Deeper inside it includes metadata sections named TLSTLIST, RLSTLIST, LIST, and tags like TRAKTRKH. Other recognizable markers are "PRTSPORT", "RGN RGNH", "XLSTGAIN", "SEND", "STRC", and "TMAP".

Adobe Capture Document

Adobe Capture Document files store data generated by the discontinued Adobe Acrobat Capture software. They serve as an intermediate working format for scanned documents before they are exported to a final format like searchable PDF. Acrobat Capture writes these files during its scan-and-OCR workflow to hold information such as recognized text zones, font data, page layout metadata, and links to corresponding bitmap image files.

When Capture runs, you typically supply scanned images (e.g. TIFF or bitmaps), then run OCR; the software creates one or more ACI image files and a matching ACD file for the same document. The ACD does not itself contain all raw image bitmap data - the referenced ACI files do that. After review and correction using Acrobat Capture tools, the ACD plus its ACI images are used to produce the final output, such as a searchable PDF.

Adobe Capture Document files are proprietary, multipage binary files. They always require at least one linked ACI bitmap image file. Internally ACD files begin with the byte signature 0x02044747C900 at offset 0 in the file and include strings such as "CAPTURE2" and ".ACI" which refer to the associated image data.

Alan 2 Code

ACD files contain the game files that are saved by Alan, a program used to create interactive fiction games. The developers of Alan combined a programming language with a set of tools to allow you to play or create text-based adventure games. These tools consist of compilers, various interpreters, an IDE (Integrated development environment), map generators, and more. Alan is still in BETA form, and the developers are working daily to fix the bugs and add new features.

RSLogix 5000 Program

These ACD files are archive files used by RSLogix 5000, a program used to create programs for your PLCs (Programmable Logic Controllers). Relay ladder, structured text, sequential function chart, and function block diagram are the programming languages used to create your ideal PLC program. This software allows you to focus more on PLC programming logic rather than wasting your time on complex syntax. To better your programming experience, you get access to drag-and-drop editing, search-and-replace functions, and tools to verify your program before running it. After the discontinuation of RSLogix 5000, Studio 5000 has taken its place.

Sonic Foundry Acid music

Sonic Foundry Acid music files with the extension .acd are project files used by the ACID family of digital audio workstation (DAW) software. These files store information about a music project such as which audio tracks are used, where they are placed on the timeline, how they are mixed (volume, pan), which effects are applied, the tempo, and other editing decisions. They do not normally hold the audio recordings or samples themselves - those are linked externally, so the .acd file acts like a map of the project rather than the content collection.

These project files are written by ACID software (originally by Sonic Foundry, later Sony, now Magix), when a user creates or edits a track-based or loop-based music composition. They are saved during the production process and can be opened later to continue work, bounce or render the project into standard audio formats like WAV or MP3, or export it for multimedia applications. When saving, there is an option (in newer versions) to embed all audio files into the project, producing a bundled file (.acd-zip), which ensures portability and prevents missing external references later.

At the technical level, these .acd project files use a RIFF-based container, beginning with the ASCII signature "riff" at offset 0. They include identifying strings such as "M'A'D'E' W'I'T'H' S'O'N", "A'C'I'D", "BLIST", "RIFF.", and chunks labelled "INAM", "IART", "ICMT", "ICOP", "IENG". These signatures help software recognise the file as an ACID project.

Various apps that use files with this extension

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