QVX: Stands for Qlikview Data Exchange (If you wish to make your own connector that could create a connectivity to Qlikview files, One of the efficient and optimize way to fetch data from the database. Mainly used if you are not using ODBC/OLEDB)
QlikView Data (QVD) files are used to extract and store data into and from
QlikView data eXchange (QVX) files are used for data input from external
systems into QlikView. The main difference with respect to the QVD file is that
QVX is a public format and can be created from external interfaces.