Windows Catalog File
| Developer | Microsoft |
| Popularity |
3.7 | 58 Votes |
What is a CAT file?
A CAT file is a Windows catalog file used by the Windows operating system to authenticate the source of a group of files. It contains a digital signature, catalog version, and effective date, ensuring that the files originate from a verifiable source. CAT files are primarily used for security purposes, often for verifying new software update files.
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Developers or organizations that distribute software produce CAT files to maintain system security and efficiency. CAT files reside in the System32 directory and are commonly associated with software installations and updates.
The files help reduce the number of trust dialog popups that occur when downloading new software components. By verifying a trusted source via a CAT file, users can select the "Always trust content" option from the software distributor, which streamlines future downloads from that source by eliminating the need for additional trust confirmations.
How to open a CAT file
CAT files are not designed to be opened directly. Instead, Windows uses CAT files packaged with drivers, software, or system components to verify their authenticity and integrity through digital signatures.
However, you can use CertUtil in Command Prompt on Windows to view information about a CAT file, such as its hash and signature details. For example, CertUtil can help determine whether the catalog file is valid and properly signed. Alternatively, developers can use SignTool (included with the Windows SDK to inspect or verify CAT files as part of driver or software package validation.
Programs that open CAT files
Advanced Disk Catalog Database
| Developer | Elcomsoft |
| Popularity |
3.0 | 17 Votes |
Contains a catalog of data from various media types including hard drives, network drives, floppy disks, optical discs (DVDs, CDs, etc.), ZIP and JAZ disks, etc.; used for keeping track of information stored within a collection of media
Programs that open CAT files
Compiled Action Tree File
| Developer | Rockstar Games |
| Popularity |
2.0 | 1 Vote |
A CAT file may also be a game data file used by Bully (released as Canis Canem Edit in some regions). It stores compiled action tree data that helps control character behaviors and other AI-driven actions within the game. Rather than containing graphics, audio, or level data, CAT files define how characters react to events and interact with the game world during gameplay.
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Bully uses CAT files as part of its internal game logic system. The game reads these files to determine how non-player characters (NPCs) behave in different situations, such as responding to the player's actions, following schedules, or participating in scripted events.
The files are primarily used by the game itself, but they have also become important to the Bully modding community. Modders may modify the behavior data to create custom gameplay experiences, adjust character actions, or experiment with the game's AI systems.
How to open a CAT file
CAT files are not meant to be manually opened. Instead, the CAT files are saved in a compiled binary format that the game references to load their information during gameplay.
However, you can use modding tools to convert CAT files into editable formats that expose the underlying action tree data, allowing you to make changes before recompiling the files for use in the game. For example, you can use Marcdred's bully-mact-tool to convert CAT files to .MACT files, and then use text editors, such as Notepad++ and Microsoft Visual Studio Code, to edit the converted data.
How to convert a CAT file
Marcdred's bully-mact-tool can convert CAT files to MACT files. After conversion, you can modify the MACT file with a text editor and then convert it back to a CAT file with the bully-mact-tool.