GstarCAD Uses CAD SDK
GstarCAD builds add-on using CAD SDK 
Suzhou Gstarsoft Co., Ltd develops 2D and 3D CAD software and solutions for the AEC, mechanical, manufacturing, electrical, GIS, civil, survey and mapping engineering industries. With more than 18 years of technology innovation and practical application, GstarCAD software is dedicated to providing the fast, powerful and DWG-compatible CAD software for customers and partners worldwide
GstarCAD has built our pdf2cad functionality into a tightly integrated add-on to GstarCAD called PDFtoDXF. Contact your GstarCAD reseller today and ask for GstarCAD PDFtoDXF!