XDrawChem

XDrawChem is a free software program for drawing chemical structural formulas, available for Unix and macOS. It is distributed under the GNU GPL. In Microsoft Windows this program is called WinDrawChem.^[1]

XDrawChem 1.9.9
Stable release	1.10.2 / January 9, 2017; 8 years ago (2017-01-09)
Repository	github.com/bryanherger/xdrawchem
Written in	C++
Operating system	UNIX and X Window (Linux, SGI IRIX, Sun Solaris, others...) or macOS
Type	Molecular editor
License	GNU GPL

Major features

• Fixed length and fixed angle drawing
• Automatic alignment of figures
• Detection of structures, text, and arrows, and their automatic 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 on CAS number, formula, or name
• Retrieval of information on a molecule based on a drawing
• Symbols such as partial charge and radicals
• Reading MDL Molfiles, CML (Chemical Markup Language), ChemDraw binary format, ChemDraw XML text format^[2]
• Writing MDL Molfiles, CML, ChemDraw XML text format
• Integration with OpenBabel, allowing XDrawChem to read and write over 20 different chemical file formats.
• Image export in Portable Network Graphics (PNG), Windows bitmap, Encapsulated PostScript (EPS), and Scalable Vector Graphics (SVG)
• 3D structure generation with the help of the external program BUILD3D
• Simple spectra predictions, including ¹³C-NMR, ¹H-NMR (based on additive rules and functional group lookup methods), and IR^[3]
• Simple property estimation, including pK_a, octanol-water partition coefficient, and gas-phase enthalpy change.