The database is populated using the Vulkan Hardware Capability Viewer application, available for multiple platforms. It reads and displays Vulkan related information for a selected implementation, and that data can then be uploaded to the database.
The Vulkan Hardware Capability Viewer is open source, you can always build the most recent version yourself using the sources from the repository.
Windows 32-bit (zip) Please note: The 32-bit windows release should only be run on platforms that don't support 64-bit! Some Vulkan implementations may not expose all hardware capabilities when run under 32 bits.