Files with the .TWBX extension contain a full set of data for the file format in which projects of the Tableau Desktop application used to create whiteboard projects are saved. The data stored in TWBX is a TWB workbook with all the external data it may refer to.

TWBX files are used to pack all data, including external data, into one file for further sharing with others. This is a fundamental difference between them and TWB files, which can only store references to external data sources and not these data directly.