AIU File
What are AIU files and how to open them
Are you having problems opening an AIU 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 AIU files.
What is an AIU file?
An .AIU file is an Advanced Installer Updates Configuration file.
Advanced Installer Updates Configuration files store information about software updates for programs built with Advanced Installer by Caphyon. These files tell the program updater what the newest version is, where to download it, what its size is, and optionally include release notes, version number, registry keys used, features changed or added, and a description of the update. Perfect when you want your software to check automatically for newer versions and retrieve them.
The files are created by Advanced Installer during the build of an Updates Configuration project. When a software developer publishes an update, they host this Updates Configuration file on a server. The installed software's updater references the file using a URL embedded in the installer setup so it can check the hosted configuration, compare versions, and download the new installer if needed.
Internally the file uses the standard Windows INI format, with one or more sections - one section per available update, plus an optional "General" section for settings that apply globally. The first line must be the exact signature ";aiu;" or else Advanced Installer's updater will ignore the file.
The file begins with a byte signature at offset zero: the ASCII characters for ";aiu;" ("3B 61 69 75 3B").
How to open AIU files
Important: Different programs may use files with the AIU file extension for different purposes, so unless you are sure which format your AIU file is, you may need to try a few different programs.
We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!
Last updated: August 17, 2026
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