One of them is Windows Installation Media Creation Tool.
It's an official Microsoft tool and it has a huge benefit:
it allows to download official Windows 8.1 installation ISO images in over 35 languages and both 32-bit and 64-bit without having to enter the product license key.
This was no possible before.
It also allows to create bootable USB flash drive.
Of course later, at the begining of the installation process, you'll have to enter the Windows 8.1 product license key.
Another benefit: to create installation media for Windows 8.1 is allowed on a Windows 7 workstation as well not just on Windows 8.1.
Limitations compared with other similar softwares:
-You can’t use Windows Installation Media Creation Tool to download Windows 7 ISO from Microsoft. Also, this tool can’t be used to download Windows 8 ISO files.
-Supported Windows 8.1 versions:
Windows 8.1 N
Windows 8.1 Pro
Windows 8.1 Pro N
Windows 8.1 Single Language editions
-It doesn't work behind proxy server.
It's simple to use:
Just download Windows Installation Media Creation Tool-t from Microsoft.
After downloading click mediacreationtool.exe, choose the right language, Windows 8.1 version and pick 32-bit or 64-bit version.
You can download Windows 8.1 ISO image, then you can burn it to DVD, or download ISO and the software will create a bootable Windows 8.1 USB flash drive.
Minimum size of USB drive is more than 4 GB.
The whole procedure is automatic, but i made some screenshots.
First about dowloading ISO image, then creating a bootable USB flash drive.
Downloading DVD ISO:
Create bootable Windows 8.1 installation USB flash drive:
Source: INTO Windows