APL File

What are APL files and how to open them

Are you having problems opening an APL 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 APL files.

What is an APL file?

APL files have multiple uses, and ACDSee plugin is one of them. Read more about the other uses further down the page.

ACDSee plugin

ACDSee, a popular photo studio software, is identified with .apl files. APL files belong to a group of files called plug-ins. ACDSee users use plug-ins to alter photos before saving or printing them.

APL plug-ins function by the following commands executed by ACDSee users:

1. Saving files to a disk.
2. Converting an image file to another format.
3. Applying filters that enhance or beautify the image.

How to open APL files

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

Last updated: August 18, 2026

All known file formats using extension .APL

While ACDSee plugin is a popular type of APL-file, we know of 8 different uses of the .APL file extension. Different software may use files with the same extension for different types of data.

ArcPad Layer

APL files are files of the ArcPad software. ArcPad is a mobile geographic information system (GIS) software used in mapping applications. APL files are necessary for saving work done on the ArcPad software. These APL files act as ArcPad layer files, elements of the image containing characteristics like brightness, contrast, transparency, scale, etc.

ArcPad is used by field-based personnel to collect data for GPS systems, digital cameras, range finders, etc. in real-time.

Authorware Library

Authorware Library files belong to Adobe Authorware, a discontinued multimedia authoring tool used to build interactive e-learning, simulation, and training content. These files serve as collections of reusable assets such as graphics, sounds, text, video, and interaction icons. Instead of embedding each asset separately in an Authorware authoring piece, icons stored in a library can be linked from the library so that multiple parts of a course share the same assets, and edits to the library file automatically propagate to every instance of its icons.

An Authorware Library file is created inside the Authorware application via its library-creation function. Designers drag icons into it, set their individual properties (such as start or end frames for media, interaction types, or display settings), and save the result. In building an Authorware course (flowline file), icons are dragged from those libraries; the course retains only links to the library icons and their content, not full copies. Libraries may be packaged for distribution so their contents are fixed, supporting easier sharing among team members or for published delivery.

Library files differ from Authorware's flowline files in that they contain no flowline structure or sequence of icons; instead they consist solely of individual icon definitions and their content. They support embedding or linking of media, and allow assignment of icon-level properties inside the library rather than at each use. Libraries support editing until packaged.

Files of this format begin with the ASCII signature "WLIB" at offset 0 (bytes 0-3), marking them as Authorware Library files.

Extra! For Windows APL Keymap

We know that one APL format is Extra! For Windows APL Keymap. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

HALNOTE Application

.apl files are executable application files used by the Halnote software. These application files are necessary to run specific programs used by Halnote.

Halnote is a graphical environment system created by Japan-based Hal Laboratory in 1987. With Halnote, users found it more pleasing to use the computer that was easier to the eye, as the graphics were more user-friendly. Halnote's graphical environment replaced the DOS's black and white visual environment.

Halnote would then be succeeded by the MSX-View which had a better graphic environment.

Monkey's Audio Image Link File

.apl files are audio image link files used by Monkey's Audio. Monkey's Audio is an application designed to compress music files. Audio image link files are files ripped from a source, for example, a music CD.

The .apl files are created using Monkey's Audio, the application compresses the audio or image, from the source, which can then be copied or converted into another audio format using your computer.

PaintSpa Palette

PaintSpa Palette files store color swatches used by PaintSpa for Windows (part of the Nimbus/SPA "PaintSpa" painting program), representing the custom artist's palette of colors available for drawing and painting. The palette allows users to pick, reuse, and preserve color choices across sessions in PaintSpa's art projects.

These files are created by PaintSpa itself (the Windows version) when a user saves or customises the canvas palette. PaintSpa reads the palette so it can display the saved colours for selection in its colour chooser, flood fill, brushes, shape borders, etc.

The file is binary and begins with a specific ASCII header string to identify it: "PaintSpa for Windows artist's palette". This signature appears at offset 0 of the file.

Team Developer / SQLWindows Application

The binary application library format known as Team Developer / SQLWindows Application produced by Gupta Technologies describes a compiled component library used with the SQLWindows (also called Team Developer) rapid application development system for Microsoft Windows. It is a binary library of reusable code and UI components (such as functions, classes, dialogs, windows, table windows, etc.) written in SAL (SQLWindows Application Language, formerly SQLWindows Application Language) which can be linked into other Team Developer applications to provide shared functionality. It allows developers to share and reuse functionality across applications by including or exporting objects like global functions, window functions, dialogs, classes and forms.

This format is created and used by Gupta's Team Developer during normal development and build workflows. Source code, resource definitions and interface objects are defined in the IDE, then saved as a binary library file. Other application projects include or link to this binary library so that the objects and code within are compiled and used at run-time. In many cases these libraries come in companion to Dynalibs (.APD files), which are compiled dynamic libraries exported from such application libraries; the application library can be saved in either compiled or "normal (binary)" form.

Internally this format starts with a specific magic signature: the first four bytes are the ASCII letters "MGDR" (bytes 0x4D 0x47 0x44 0x52) at offset zero.

Various apps that use files with this extension

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

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