Molecules vs Molecular Constructor

Molecules is an application for viewing three-dimensional renderings of molecules and manipulating them using your fingers. You can rotate the molecules by moving your finger across the display, zoom in or out by using two-finger pinch gestures, or pan the molecule by moving two fingers across the screen at once. These structures can be viewed in both ball-and-stick and spacefilling visualization modes. Molecules can be stored on your handheld device for later viewing and are loaded via a standard document-based file browser. Custom molecular structures can be downloaded to the application via file sharing or iCloud, and obtained via sources like the RCSB Protein Data Bank (http://www.rcsb.org/pdb), an international repository of biological molecules and their 3-D structures, or NCBI's PubChem (http://pubchem.ncbi.nlm.nih.gov), a public database of compounds. For more details, please visit our website. Molecules is a BSD-licensed open source project.

Molecular Constructor is a free 3D modeling software for building molecules. Using this application user can design a molecule and optimize its geometry at the same time. The more advanced desktop version can be found at the project website: http://molconstr.com/