gibMacOS: Downloading macOS Installer Components Directly from Apple's Catalog

What gibMacOS does and who uses it

gibMacOS is a Python script that contacts Apple's software update catalog and downloads macOS installer components to a local machine. It works on macOS and on Windows, which is the property that makes it useful for Hackintosh builders who need a genuine Apple-sourced installer without access to a running Mac.

The most common uses are fetching a clean macOS installer for reinstalling the operating system, downloading a version of macOS that is no longer available through Software Update, and preparing USB installation media for a machine that lacks a working operating system. The script retrieves components directly from Apple, so the downloaded files are the same ones Apple distributes through its official channels.

The repository was written by Taehoon... Wait, no - this is the corpnewt repository, written by the corpnewt author. The README credits FoxletFox for FetchMacOS and for documenting the URL structure, munki for macadmin-scripts, timsutton for brigadier, and wolfmannight for manOSDownloader_rc, which BuildmacOSInstallApp.command is based on.

The repository contains six scripts: gibMacOS.command and gibMacOS.bat for macOS and Windows entry points respectively, gibMacOS.py for the core logic, MakeInstall.bat and MakeInstall.py for building Internet Recovery USB drives on Windows, and BuildmacOSInstallApp.command for assembling the macOS installer application on macOS from downloaded components.

Running gibMacOS on macOS and on Windows

On macOS, the intended entry point is gibMacOS.command, which can be double-clicked in Finder to run the script without opening a terminal manually. The underlying Python script can also be run directly:

python gibMacOS.py

On Windows, gibMacOS.bat is the entry point. The script queries Apple's catalog, presents a list of available macOS versions, and downloads the selected components to a local directory. The README does not document additional command-line flags for gibMacOS.py itself, but the .command and .bat wrappers handle environment setup for each platform.

For building a macOS install application on macOS from the downloaded components, BuildmacOSInstallApp.command performs that assembly step. On macOS 11 Big Sur and later, that step is unnecessary because Apple changed the distribution format; running the downloaded package directly handles the installation. Running BuildmacOSInstallApp.py is the cross-platform version of the same assembly operation.

The README does not specify minimum Python versions beyond Python 2 or Python 3, and it does not list pip dependencies for the main download functionality. The script targets Apple's catalog endpoints directly, so no third-party API keys or authentication are required.

The Windows USB installer path: MakeInstall and the dd dependency

Building an Internet Recovery USB installer on Windows requires two additional tools that gibMacOS does not include: dd for writing disk images and 7-Zip for extracting archives. The README links to the chrysocome.net distribution of dd and to 7-zip.org for the download. Once those tools are installed and available, MakeInstall.bat or MakeInstall.py handles the disk writing process.

This path works for macOS versions through Catalina (macOS 10.15). The README states explicitly that as of macOS 11 Big Sur, Apple changed the way it distributes macOS, and internet recovery USB drives can no longer be built via MakeInstall on Windows for Big Sur or any later version. Only macOS versions through Catalina will still work through this method.

For users on Windows who need a Big Sur or later installer, the correct path is to download the installer using gibMacOS and then use a running Mac or a macOS virtual machine to create the USB drive. The README does not document an alternative Windows-only path for Big Sur and later.

The Big Sur distribution change and InstallAssistant.pkg

Prior to macOS 11 Big Sur, Apple distributed macOS installers as a bundle of component files that BuildmacOSInstallApp.command assembled into the final Install macOS application. gibMacOS was designed around this structure.

With Big Sur, Apple switched to distributing macOS as a single InstallAssistant.pkg file. When gibMacOS downloads a Big Sur or later installer, the result is this package file rather than the older component structure. The README notes that BuildmacOSInstallApp.command is not needed in this case. Running InstallAssistant.pkg directly on macOS places the install application in the /Applications folder, ready for use.

This change also affects the MakeInstall workflow on Windows. The older process relied on the component structure to write a bootable USB drive; the InstallAssistant.pkg format does not support the same process. Anyone using gibMacOS on Windows should read the three-note section at the top of the README before starting, since the applicable workflow depends on which macOS version is being downloaded.

The malware warning: why the source of the download matters

The README includes a note that others have distributed modified versions of gibMacOS under its name, and that at least some of these redistributed copies have been used to deliver malware. The README explicitly states: "Valid copies of the script can always be retrieved here on GitHub" and advises against using any third-party rehosts.

This warning is relevant for anyone finding gibMacOS through a search engine or a forum link. The SHA of the files in the official repository at github.com/corpnewt/gibMacOS is the only authoritative source. Running a copy from a third-party download site, even one that appears identical, carries a meaningful risk. The script runs with the permissions of the user who executes it and makes network requests to Apple's servers; a modified version could intercept or replace those requests or run arbitrary code.

For Hackintosh use specifically, the community reliance on this tool has made it a target for impersonation. Verifying the source before use is a concrete and necessary step.

munki macadmin-scripts as an alternative for managed deployments

munki's macadmin-scripts is an alternative that the gibMacOS README acknowledges directly as an influence. macadmin-scripts targets Mac administrators in enterprise and education environments who need to download, cache, and deploy macOS installers across a fleet of managed machines. It is a collection of scripts oriented around the Munki software management system and focuses on scripted, repeatable downloads for deployment pipelines rather than interactive selection.

The difference in approach is the intended audience. gibMacOS is designed for individual use with an interactive interface that lists available versions and lets the user select one for download. macadmin-scripts is designed for IT operations where the download needs to run as part of an automated workflow without interactive prompts. Someone setting up a single machine or building a Hackintosh will find gibMacOS's interactive approach more convenient. A Mac administrator managing dozens of machines through Munki should look at macadmin-scripts instead.

Both tools pull from Apple's catalog, which means both receive the same installer files. The distinction is entirely in how the download is triggered and what the output is used for.

Editorial conclusion

gibMacOS is the right tool for engineers and Hackintosh builders who need to download specific macOS versions directly from Apple's catalog on either macOS or Windows. It is the correct choice for building Internet Recovery USB drives on Windows for macOS versions up to Catalina. It is not the right tool for building Internet Recovery installers on Windows for macOS 11 Big Sur or later, because Apple changed its distribution format and MakeInstall no longer works for those versions. Before downloading the script, verify you are using the official repository at github.com/corpnewt/gibMacOS: the README warns that others have distributed malware under the gibMacOS name through third-party sources.

Frequently asked questions

Official sources

1. corpnewt/gibMacOS on GitHub
2. Issues
3. License: MIT
4. README