XFD is a Microsoft Windows-exclusive file format used by now-discontinued software application IBM Lotus Forms Viewer. XFD files were used for storing official and business documents, including those digitally signed.

XFD format used the XFDL format and saves data as plain text. XFD files were commonly used for standardized documents used by businesses and in various branches of government and military, most notably in the United States Air Force. XFD may contain sensitive transaction data.