(ideal for AutoCAD, NavisWorks and Revit), IGES solids, Parasolid, encrypted and native ProE/Creo (licensed from PTC itself), Rhino-3D, SOLIDWORKS, Solid Edge, STEP solids, STL, XGL and X3D. Dozens more file formats are also provided in the base-level PolyTrans, as well as in the DCC...
If you know anyone that has SolidWorks or someone on this site who offers, you could send them your SLDPRTs and SLDASMs and they could import them and send them back to you as STLs which you can import into FreeCAD. I might be able to convert them for you....