BDB is a file format that has been used by the Microsoft Works office software suite. Among the suite's programs was a database builder that used BDB files for backup. BDB files stored backup copies of the databases contained in WDB files. This made it possible to restore the proper database from the BDB file in case of its failure.

Both Microsoft Works and the BDB format are rarely used today and are considered obsolete. Microsoft Works was superseded by Microsoft Office, which offers many more possibilities.