You don’t need a specific software to do kufi murabba’. I used to use MS Paint to do kufi in my beginning years. Now, I’m using Gimp and Inkscape, both are freeware (legally free to download at their respective sites). If you own Adobe softwares (i.e. Photoshop or Illustrator), you can use them as well. Another person use Excel to make the design. All you need to have is a workspace with a grid.