545 File

What are 545 files and how to open them

Are you having problems opening a 545 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 545 files.

What is a 545 file?

A .545 file is an AIMutation Skin file.

The AIMutation Skin format (files with extension .545) is a skin-package used with the AIMutation plug-in for AOL Instant Messenger (AIM), designed to change the visual appearance of AIM interface elements such as menus, buttons, panels, tabs, and other UI components. It customizes how AIM looks to the user, replacing standard graphics with themed images for various UI parts.

AIMutation skins are created using its skins editor (or tools included with AIMutation), then saved into a package file with extension .545. Users install or load these files into AIMution, which reads the image assets inside and applies them to AIM's UI. The package holds all images needed - backgrounds, buttons, tabs, system buttons, etc. - so the skin works as a complete theme.

Internally the file is a ZIP-style archive starting with the PK file-header (bytes "50 4B 03 04 14" at offset 0). It contains many bitmap image assets whose filenames include ".BMPPK" (for example "BACKGROUND.BMPPK", "BOTTOM LEFT.BMPPK", etc.), as well as a configuration file "SKIN.INI" stored under a name using ".INIPK". These filenames are used by the AIMutation tool to map parts of the package to corresponding UI elements.

How to open 545 files

Important: Different programs may use files with the 545 file extension for different purposes, so unless you are sure which format your 545 file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested three different 545 openers which you will find listed below.

Last updated: August 16, 2026

Various apps that use files with this extension

These apps are known to open certain types of 545 files. Remember, different programs may use 545 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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