APT File

What are APT files and how to open them

Are you having problems opening an APT 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 APT files.

What is an APT file?

APT files have multiple uses, and Adaptive Prediction Tree Encoded Bitmap is one of them. Read more about the other uses further down the page.

Adaptive Prediction Tree Encoded Bitmap

When an image needs compression to save space, one process used is APT. The files created in the process are called .apt files. APT stands for Adaptive Prediction Tree. There are two types of image compressions for .apt files: A lossless image is a compressed image with no data from the original image discarded, and a lossy image is a compressed image with data from the original image discarded. The image quality is the same as the original for lossless compression, where lossy compression sacrifices image quality for improved space savings.

John Robinson, a researcher who focuses on image processing and analysis, developed the APT compression method.

How to open APT files

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

Last updated: August 18, 2026

All known file formats using extension .APT

While Adaptive Prediction Tree Encoded Bitmap is a popular type of APT-file, we know of 3 different uses of the .APT file extension. Different software may use files with the same extension for different types of data.

Android PandaHome Theme

A .apt file is a theme file created by the Android PandaHome. PandaHome is an Android-based application used to change themes. A theme pertains to the appearance of your Android device's look. PandaHome changes font styles, icons, wallpapers, etc that are included in the theme.

Team Developer / SQLWindows Application

Team Developer / SQLWindows Application files are source files used by Gupta Technologies' Team Developer (also known as SQLWindows) to store an application's design and logic in plain text. They capture the GUI layout, window definitions, menus, controls and code in a human-readable form for editing, version control or manual inspection. These files are written by Team Developer and are read by the same system; after editing they are compiled or run within Team Developer's environment.

Typical workflow involves creating or editing the application in Team Developer's IDE, then saving the design either in a binary format (APP) or as text with optional indentation (APT). Using the APT format makes it easier to diff, merge, or otherwise analyze changes. In more recent versions (for example Team Developer 7.0), the default format has shifted toward the text-based version (APT) rather than binary.

APT files begin with ASCII headers marking application metadata. They commonly start with a line like ApplicationDescription: at the very start of the file and include various named sections and keywords such as GLOBAL DECLARATIONS, CLASS DEFINITIONS, RESOURCES, WINDOW DEFAULTS, FORM WINDOW, DIALOG BOX and CONTROL types like PUSHBUTTON, SPIN FIELD, COMBO BOX, LIST BOX and properties like FONT NAME, FONT SIZE, BACKGROUND COLOR, TEXT COLOR. There are boundary markers like .DATA … .ENDDATA and sections for external functions, internal functions, constants, variables and so on.

Various apps that use files with this extension

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