Open Babel is a project designed to pick up where Babel left off, as a cross-platform program and library designed to interconvert between many file formats used in molecular modeling and computational chemistry.

It works in: A huge variety of common chemical file formats, including SDF/MOL, Mol2, PDB, SMILES, XYZ, CML...; Recognition of file type based on filename extension; Chemical MIME support
SMARTS matcher; Flexible atom typer; Flexible bond typer for perception of multiple bonds from atomic coordinates; Gasteiger partial charge calculation; addition and deletion; Isotope support, calculation of average and exact masses; Automatic feature perception (rings, bonds, hybridization, aromaticity); Multiple conformer storage within molecules; Command line conversion for multiple molecules in one file; Command line interface; Bitvector class; Vector and matrix transformations; Molecular test suite.