Caddie is described as 'provides designers with all the tools they need to sketch, design, detail and visualise their ideas in 2 and 3 dimensions, to produce superb quality drawings full of character and stunning 3D images that bring their designs to life'. There are more than 25 alternatives to Caddie for a variety of platforms, including Windows, Mac, Linux, the Web and Android. The best alternative is Autodesk AutoCAD. It's not free, so if you're looking for a free alternative, you could try MakerSCAD. Other great apps like Caddie are DraftSight (Paid), ArchiCAD (Paid), ZWCAD (Paid) and CorelCAD (Paid).