Official support for SmarThru 4 has largely migrated to following their acquisition of Samsung's printer division. You can typically find the software through these channels:

: Includes Optical Character Recognition to convert scanned images into editable text.

Allows you to scan documents directly to the Image Manager for editing, or route them to specific destinations.

: The most reliable way to find the version specific to your printer model is via the HP Software and Driver Downloads page.