Install macOS Big Sur on Mac [Direct Download]

The next big release of macOS is out. Apple has released macOS Big Sur for all users. And like previous years, Apple’s servers will be busy serving a high volume of download requests, at least for the first few days.

Of course, the macOS system update experience has improved greatly over time. And though you’re less likely to face download issues, such as slow downloading speeds, unable to resume download, interrupted download, frequent disconnection, etc., while downloading the Big Sur update via System Preferences or Mac App Store, it’s still probable.

Thus, many users would still look for direct download links for Big Sur, primarily for faster downloads through download managers, along with resume support in case it gets interrupted.

In this article, we’ll explore a way to download macOS Big Sur directly from the Apple server instead of via the MAS/System Preferences, using your favorite web browser or a dedicated download manager.

Note: This post is specific to macOS Big Sur direct download from Apple servers. For other macOS and OS X releases, check our earlier articles in this series.

Download and install macOS Big Sur without MAS / System Preferences

In macOS, whenever you download a new system update, some package files are downloaded to your computer, and then processed by the Software Update utility, to convert them into an executable “.app” file.

In this workaround, we’re going to directly download these raw packages from the Apple server using a web browser or a suitable download manager. Then, we’ll configure the computer in such a way that Software Update processes the package files by fetching them from a local directory on your Mac, instead of downloading it again from the Apple Server.

macOS Big Sur Direct Download

Step 1: Download the following files from the respective URLs provided below.

macOS Big Sur 11.0.1 (20B29) / November 12, 2020 (Updated)

  1. macOS Big Sur InstallAssistant.pkg file download URL:
    http://swcdn.apple.com/content/downloads/50/49/001-79699-A_93OMDU5KFG/dkjnjkq9eax1n2wpf8rik5agns2z43ikqu/InstallAssistant.pkg
  2. macOS Big Sur InstallAssistant.pkg.integrityDataV1 file download URL:
    http://swcdn.apple.com/content/downloads/50/49/001-79699-A_93OMDU5KFG/dkjnjkq9eax1n2wpf8rik5agns2z43ikqu/InstallAssistant.pkg.integrityDataV1

** Update: In earlier versions of macOS, we needed to download multiple .pkg files, which required the below steps to ultimately create the Installer.app file. However, as pointed out by Alejandro Heredia, with Big Sur, you just need to download the InstallAssistant.pkg file, run it, and complete the package installer wizard.

Once you complete the steps, you should find the Install macOS Big Sur.app file in the /Applications directory, which you can then run to install Big Sur on your Mac. If this doesn’t work for you, you may try the old method provided below.

We have compared the hashes of the Install macOS Big Sur.app files created from both the methods, and can confirm that the two files are exactly the same.

Step 2: Configure your Mac so that Software Update looks for the macOS packages locally instead of from the Apple server.

To do this, you need to edit the hosts file on Mac to point the root domain of the download URLs (“swcdn.apple.com”) to localhost (“127.0.0.1”). The below instructions will guide you to modify the hosts file as required.

  1. Launch Terminal on your Mac from Launchpad or Applications list.
  2. Type in the following command: “sudo nano /etc/hosts
  3. Provide the System Password when prompted. The hosts file is now open in editable mode within the Terminal window.
  4. Append the following line to the end of the file: “127.0.0.1       swcdn.apple.com”.
  5. Press control + X (^X), then Y, and hit return to save the file and return to Terminal prompt.

From now on, any request issued for the particular root domain (swcdn.apple.com) from the Mac will be directed to the localhost.

Note: Sometimes, you might need to flush the DNS cache for the changes to take effect. In that case, use the “sudo killall -HUP mDNSResponder” command to flush the DNS cache.

Step 3: Place the package files in a certain relative path from the localhost root, to mimic the structure of their respective download URLs.

In this example, we’ll create a folder named “macos_local” on the Desktop, and replicate the directory structure of the package URLs under the same. Once the relative path has been created, we’ll configure the localhost server to point to the “macos_local” directory on the Desktop. Then, we’ll use macOS’ built-in SimpleHTTP server to convert the folder into a web server directory.

The below instructions will guide you through the setup process.

  1. Open Terminal from the Launchpad or Applications list.
  2. Type “cd Desktop” on the command line and hit return to enter the Desktop folder.
  3. Type “mkdir macos_local” and hit return to create the root directory of the same name on Desktop.
  4. Go to the newly created folder by typing “cd macos_local” and hitting return.
  5. Enter the following command to create the relative path for the .pkg files, inside the macos_local folder (Provide the admin password when requested):
    sudo mkdir -p ./content/downloads/50/49/001-79699-A_93OMDU5KFG/dkjnjkq9eax1n2wpf8rik5agns2z43ikqu/
  6. Place the downloaded package files in their respective relative location (as per their URLs) within the macos_local folder on the Desktop. Click on Authenticate when prompted, and provide the system admin password.
  7. With macos_local as the present working directory in Terminal, execute the following command: “sudo python -m SimpleHTTPServer 80”. Provide the admin password and click on Allow in the subsequent message prompt.

The current directory (macos_local) is now hosted on the localhost. Leave the Terminal window open to keep the localhost server running until the process is completed.

To verify the setup, click on any of the package (.pkg) URLs in your browser and check the download speed as it downloads the package.

You may notice a very high-speed download (which is much higher than the speed of your Internet connection). This is because the file will be downloaded through the localhost; your Internet bandwidth won’t be used.

Step 4: Download macOS Big Sur through the Mac App Store or System Preferences.

Since you’ve redirected the package URLs locally, Software Update / MAS will fetch the package files from the localhost and launch the installer (“.app”) file once the packages have been processed.

Note: Your Mac might request additional resources from the “swcdn.apple.com” domain while installing macOS Big Sur. Thus, it is recommended to remove the entry from the hosts file that we appended earlier, before proceeding with the installation.

Is the workaround genuine?

In this workaround, we are downloading the required resources from the Apple Server and using the official Software Update channel to install the OS update. So yes, it is as genuine as the official method.

The only factor we’re changing here is the location where Software Update / MAS fetches the packages from. If you are downloading the macOS package files from third-party sources, you can verify whether it’s the original, by comparing their MD5 and SHA1 hash values.

macOS Big Sur Bootable Installer (macOS Big Sur DMG)

Now that you have the “Install macOS Big Sur.app” installer, you can upgrade multiple Macs to the latest version using the same file. However, if you are looking to perform a fresh installation, you need to create a bootable installer for Big Sur.

The bootable image for Big Sur (SharedSupport.dmg) is located within its “.app” file. To get the SharedSupport.dmg (aka. InstallESD.dmg) file, right-click on “Install macOS Big Sur.app”, select “Show Package Contents” option, and browse to the “Contents/SharedSupport/” folder.

Alternatively, the bootable installer for macOS Big Sur may be directly created from the “.app” file using the “createinstallmedia” command, as suggested by Apple.

If this workaround has helped you to get macOS Big Sur easily or saved your Internet bandwidth on single or multiple installations, let us know in the comments below.

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