MoleculeSketch

MoleculeSketch is a simple and easy-to-use molecule drawing tool for Mac OSX. Atoms and bonds are nicely positioned by locking.

The types of bonds can be changed by clicking on existing bonds. Different atom and bond attributes (like missing hydrogen atoms), non-bonding electron pairs on hetero-atoms, font size and type, bond line width or color can be accessed and changed through pop-over panels. In addition, you can add reaction arrows and text fields, while the average mass and formula of molecules can be calculated from the menu bar.