There is only one file type that uses the .NWDB extension:
Neat Database File
An NWDB file is a database file created by Neat 5, a digital document organizer. It contains one or more images of scanned documents, contacts, or receipts. NWDB files are automatically created when you scan a document.
You most likely will only see the NWDB file if you search the Neat Data folder in your Documents folder. There should be at least three files in the Neat Data folder: a Neatworks NWDB file, an image NWDB file, and a cabinet NWCAB file.
If you come across an error message indicating that you cannot open a Neat database, it most likely means that a file in your database is corrupt, locked by another program, or missing. You should check that all three files are in the Neat Data folder. If one of the three files is missing then it causes the error message.
NOTE: An NWDB file is actually a SQL Server Compact Edition (SQLCE) database but instead of the .sdf file extension, it has the .nwdb file extension. Therefore, any programs that can open .SDF SQL Server Compact Database files can also open NWDB files.
ImageDB1.nwdb - The default name given to an NWDB file. If there are multiple, the files are named "ImageDB2.nwdb", "ImageDB3.nwdb", etc.
Updated: March 24, 2019