A file with .igs (Initial Graphics Exchange) extension is a 2D-3D design exchange file format that is independent of source or destination file format specifications used by CAD applications. It is used to exchange design information about circuit diagrams, wireframes, the freeform surfaces between two independent systems. IGS files can be opened by applications such as Autodesk, FreeCAD, CADEX CAD Exchanger, and other similar applications.
XLAM files are used to extend the modules provided by Excel. They can be added to Excel 2007 or later, or to earlier versions of Excel with Open XML component support. File used by Microsoft Excel, a program that allows users to create and edit spreadsheets; contains a macro-enabled add-in, which provides extra functionality and tools that may execute macros.
You can also convert IGS into many other file formats. Please see the complete list below.