Finding the official has become a notorious headache. Microsoft officially ended support for Visual Studio 2010 in July 2020, removing direct public links to the standalone "Build Tools." However, building legacy C++ projects (especially via CI/CD pipelines using MSBuild v4.0) still requires the v100 platform toolset.
The most official way to get these tools is by downloading a legacy version of Visual Studio. : Sign up for the free Visual Studio Dev Essentials : Once logged in, go to the Older Downloads page and search for Visual Studio 2010 Installation : Installing any edition (even Express) will register the v100 toolset Visual Studio 2010 Build Tools V100 Download
A community-maintained automated method exists using the command choco install vcexpress2010 to install the Visual C++ 2010 Express edition, which includes the v100 tools. Stack Overflow Why Developers Still Use the v100 Toolset Finding the official has become a notorious headache