U3D is na universal format supported by various CAD software. U3D file stores compressed data of 3D model. U3D format is typically used for exchanging 3D data between different applications.

U3D format specification was developed by a consortium of companies (Intel, Boeing, HP, Adobe Systems, among others) and then standardized by Ecma International and designated as ECMA-363. Objects in U3D files can be added to PDF files and viewed in Acrobat Reader (version 7 and later).