The ArcObjects SDK is not a standalone public download; it is bundled with the main ArcGIS Desktop installation files.
If you're developing with Visual Studio, you might also find the ArcObjects SDK through: arcobjects sdk 10.8 download
Before clicking any download link, it’s crucial to understand what the SDK is—and what it is not. The ArcObjects SDK is not a standalone public
Version 10.8 is significant because Esri announced that ArcGIS Desktop 10.8.x is the final release series for the classic ArcMap platform. Support for 10.8.1 and 10.8.2 continues through the standard lifecycle, but no new features or major SDK updates will follow. Therefore, many developers are standardizing here for long-term maintenance projects. Version 10