MIFit is a cross-platform interactive graphics application for molecular modeling, fitting, and refinement of protein structures from x-ray crystallography.

MIFit has been released as open source by Rigaku under the GNU General Public License.

The binaries available are for MIFit 8, but the source code is for MIFit 9.b1. Prior to release as open source, MIFit was undergoing conversion to the Qt Cross-Platform Application Framework. Although this new version is complete, it is considered beta software, since it has not been fully tested and it is missing some functionality in the previous version (hardware stereo and sequence view). Binaries of version 9 will be available after more of conversion issues have been eliminated.