XDrawChem is a free software program for drawing chemical structural formulas, available for Windows, Unix, and Mac OS. It is distributed under the GNU GPL. Major features Fixed length and fixed angle drawing Automatic alignment of figures Detection of structures, text, and arrows, and their automatically placement Can automatically draw rings and other structures - has all standard amino acids and nucleic acids in a built-in library Retrieval of structures from a network database based o… (More on Xdrawchem)