BioJava aims to provide a comprehensive set of Java components for the rapid development of applications in Bioinformatics. It contains interfaces for representing Sequences, Features, and other important bioinformatics concepts. It can also read and write sequence data in a variety of common formats and communicate with Ensembl databases and with DAS and BioCorba servers.
Ghemical is a molecular modelling software package with some nice 3D visualization tools. It supports methods based on both molecular mechanics and quantum mechanics (using MOPAC7, and MPQC for QM). The geometry optimization (for MM and QM) and molecular dynamics (for MM) algorithms are included. Ghemical is written in C++, and hopefully offers a good framework for a generic freeware molecular modelling tool.
Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
Viewmol is a program for building and editing molecules as well as for the visualization of outputs from quantum chemical and molecular mechanics programs. Currently supported are Gaussian 9x, Gamess, Discover, DMol/DSolid/DMol3, Gulp, Mopac, Turbomole, and PDB files. Properties visualized include geometry (with various drawing modes), vibration (animated or with arrows), optimization history/MD trajectories, MO energy level diagram, MOs, basis functions, and electron density. Drawings can be saved as TIFF, HPGL, Postscript, and input files for Rayshade. Viewmol has an embedded Python interpreter for automation. The program is language independent and currently "speaks" English, French, German, Russian, or Spanish.
VMD (Visual Molecular Dynamics) is designed for the visualization and analysis of biological systems such as proteins, nucleic acids, lipid bilayer assemblies, etc. It may be used to view more general molecules, as VMD can read standard Protein Data Bank (PDB) files and display the contained structure. VMD provides a wide variety of methods for rendering and coloring a molecule: simple points and lines, CPK spheres and cylinders, licorice bonds, backbone tubes and ribbons, cartoon drawings, and others. VMD can be used to animate and analyze the trajectory of a molecular dynamics (MD) simulation. In particular, VMD can act as a graphical front end for an external MD program by displaying and animating a molecule undergoing simulation on a remote computer. VMD uses OpenGL and OpenGL Programmable Shading Language for high performance rendering of large structures.
XDrawChem is a program for drawing chemical structures. Features include fixed length and fixed angle drawing, a ring tool to automatically draw rings, automatic alignment of structures in reactions, 2D structure diagram generation, and 3D structure conversion. It can access structures in the PubChem compound database by name, CAS number, or formula. It can output InChI for structures and search the database by structure. It can predict 1H NMR, 13C NMR, simple IR spectra, and estimated pKa. XDrawChem can work with its native file format, ChemDraw files, and any format supported by OpenBabel (MDL Molfile, CML, etc.).