Microsoft hid it on a legacy server. The official filename you are looking for is: MediaCreationTool.exe for Windows 8.1 (specifically version 9600).
Public repositories like Internet Archive host community-preserved copies of the official Microsoft ISOs. These are often used by enthusiasts for virtual machines or testing, though they are not hosted on Microsoft servers. How to Create Bootable Media Manually windows 8.1 download 64 bit media creation tool
Despite the release of Windows 10 and Windows 11, millions of users still rely on Windows 8.1 for its unique balance of speed, low system requirements, and the nostalgic "Start Screen" experience. However, finding a legitimate has become increasingly difficult. Microsoft officially ended mainstream support for Windows 8.1 on January 10, 2023, and the dedicated "Media Creation Tool" for 8.1 is no longer hosted on the front page of Microsoft’s website. Microsoft hid it on a legacy server
Choose "Windows 8.1" (or "Windows 8.1 Pro" if available) from the dropdown. These are often used by enthusiasts for virtual