macOS Downloader "is a command line tool for downloading macOS installers and beta updates".
installinstallmacos.py "can create disk images containing macOS Installer applications available via Apple's softwareupdate catalogs". Note that "Since it is using Apple's installer, any install check or volume check scripts are run. This means that you can only use this tool to create a diskimage containing the versions of macOS that will run on the exact machine you are running the script on. For example, to create a diskimage containing the version 10.13.6 that runs on 2018 MacBook Pros, you must run this script on a 2018 MacBook Pro, and choose the proper version. ... Use a compatible Mac or select a different build compatible with your current hardware and try again. You may also have success running the script in a VM; the InstallationCheck script in versions of the macOS installer to date skips the checks (and returns success) when run on a VM."
Apple Installer Checksums offers "SHA1 checksums of Apple's installers for Mac OSX InstallESD.dmg and Xcode Installer DMGs".
macOS Big Sur Full Installer Database. Download Directly from Apple!
UPDATE: See also Microsoft ISO checksums/hashes for Windows, Office, etc.
/mac | Jun 04, 2019