ACP File

What are ACP files and how to open them

Are you having problems opening an ACP 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 ACP files.

What is an ACP file?

ACP files have multiple uses, and Action! Presentation is one of them. Read more about the other uses further down the page.

Action! Presentation

Action! Presentation files with the ACP extension store multimedia slide show documents created by Macromedia Action! (version 2.5). These files were designed in the early 1990s as content created in a presentation authoring tool for Windows 3.x. The software enabled users to create animated and interactive presentations combining text, graphics, sound, and video elements. Macromedia Action! was the program that wrote these ACP files.

Each ACP file contains all the data needed to play or edit the presentation - slides, animations, transitions, embedded multimedia, and interactive components. The workflow is that a user creates or edits the presentation using Action! version 2.5, saving it as an ACP file; later it could be viewed or presented via Action! or viewers that support that format. Because Action! is no longer sold, ACP files are legacy documents for preserving or accessing old multimedia presentations.

On the technical side, these ACP files use the RIFF (Resource Interchange File Format) container structure. Early bytes of the file include the ASCII signature "RIFF" at offset 0, "oakt" at offset 8, and internal keywords include strings like "ACTR", "SCENE", "DOCUMENT", "DBID", "FMTB", "OAKT", "OTSC", "PRVT", and "PRXY" which help identify the content and structure inside the file.

How to open ACP files

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

Last updated: August 17, 2026

All known file formats using extension .ACP

While Action! Presentation is a popular type of ACP-file, we know of 3 different uses of the .ACP file extension. Different software may use files with the same extension for different types of data.

ArCon project

These ACP files contain the 3D building plans/layouts you created using ArCon Project, a software used by architects, interior designers, and homeowners to plan and present their designs. ArCon makes use of 3D technology to help you visualize your creative ideas. You do not need any CAD knowledge; you get access to construction elements that you can place down. ArCon is user-friendly, and you do not need any formal training/education to use the software. You can design your exterior and interior with easy-to-use construction software.

EditPlus Auto Completion

EditPlus Auto Completion files enable the text editor EditPlus to expand short abbreviations into longer text snippets automatically, saving typing effort while writing code or text. These files are created and read by EditPlus on the Windows platform. When the user types a defined abbreviation (trigger) and presses space or tab, EditPlus replaces it with a longer predefined text, possibly moving the cursor to a "hot spot" in the expanded text. ACP files allow customizing this behavior for different file types.

ACP files are plain text documents written by users or bundled with EditPlus. They follow a simple syntax that begins with header directives telling the title (#TITLE) and whether triggers are case-sensitive (#CASE=y or n). After the header, each "text clip" starts with a trigger label using "#T=triggername" and is followed by the replacement body. The body can span multiple lines and include special markers: "^!" for cursor placement ("hot spot"), "^^" to encode a literal caret character, and "^#" or "^;" to escape pound or semicolon when used in output. Users can add ACP files via the Settings & Syntax preferences of EditPlus.

Files of this format usually begin with the ASCII string "#TITLE=" at offset zero, and include the string "CASE" in the header to indicate the case sensitivity directive.

Various apps that use files with this extension

These apps are known to open certain types of ACP files. Remember, different programs may use ACP 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 ACP file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.