VDX (standing for Virtual Document eXchange) is a software product for interlibrary loan (ILL) and document request management. VDX was developed by UK company Fretwell-Downing Informatics, a company which in 2005 was taken over by OCLC PICA, itself wholly acquired by OCLC Online Computer Library Center in 2007.VDX allows library staff to create and manage document borrowing and lending requests between participating libraries. VDX manages all the stages of the ILL process.