APWZ File

What are APWZ files and how to open them

Are you having problems opening an APWZ 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 APWZ files.

What is an APWZ file?

An .APWZ file is an Aspen Plus Compound Document file.

Aspen Plus Compound Document files are simulation packages produced by Aspen Plus that bundle everything needed to reproduce a chemical process model in one place. These files store full input specifications, the results produced by the simulation, and intermediate data related to convergence. They also include external resources that the model depends on, such as user-written subroutines, design or rating files, embedded spreadsheets, and other auxiliary files. Their primary purpose is to consolidate all assets of a simulation for portability, archiving, or transferring between setups.

The files are created by selecting the compound-file save option in Aspen Plus. When saving, Aspen Plus attempts to locate every file that the simulation references; files in the same folder (or subfolders) and referenced by relative paths are embedded inside the compound document, while externally referenced files via absolute paths are linked rather than stored. Within the compound file, filenames for internal backup (.bkp) or document (.apw) files are updated if the compound file itself is renamed. These files support later editing of their contents (adding, removing, or extracting dependencies) via the Edit Compound File command in Aspen Plus.

This format uses binary storage. Its structure begins with the signature bytes "PK 0x03 0x04" at the start, implying ZIP-compatible packaging, and it contains identifiable internal strings such as "ASPEN_COMPOUND_FILE_SETTINGS_V1.0--" and markers ".APWNU" or "NUCX," which help the application detect that the compound file is in the correct format.

How to open APWZ files

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

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

Last updated: August 18, 2026

Various apps that use files with this extension

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