Ketcher

Ketcher Features:
Creating, saving and sharing chemical structures
You can create chemical structures from scratch, open them from a chemical file (mol, mol3000, rxn, rxn3000, smiles, inchi, and cml formats are supported), or import a drawing from a PNG image file. When you are done, you can save the drawing as an RXN chemical file and/or share it via email.
 
Selecting and editing
You can select rectangular or free-form areas of the drawing and perform various operations with them (cutting, copying, pasting, or deleting). You can move and rotate selections as well as the whole structure. The application saves editing history as you are working, so you can undo up to 32 changes.
 
Working with atoms
You can select atoms from the periodical table and paste them onto the empty drawing canvas or replace other atoms. You can also add atoms to a structure by tapping and drawing from an atom already present. If you tap and hold an atom, you can edit its properties (charge, valence, isotope, and radical).
 
Other elements
Ketcher supports further elements for drawings:
* bonds (multiple, editable bond types and chains of bonds are supported)
* R-groups
* templates
 
Reactions and layout enhancement
You can draw reactions and map the atoms from the reagents to the product manually or automatically. The drawings can be automatically “cleaned up”.  
 
Internet access
Most of Ketcher functionality is available offline, but you need Internet access for the following operations:
* Open and save inchi and smiles chemical files
* Import of drawings from PNG files
* Clean-up (smoothening) of drawings
* Automatic reaction mapping