.$DB File

The $db file extension is mainly related to dBASE IV database program and used for one of its temporary files.

These are typically created by computer programs for a variety of purposes; principally when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than architecture's address space, or as a primitive form of inter-process communication.

How to open:

In vast majority of cases, users cannot access temporary saved data.

How to convert:

Temporary files are usually not meant to be converted to anything else.