Spglib is a library for finding and handling crystal symmetries written in C. There are the python, fortran, and ruby interfaces. Version history is found at ChangeLog.
The detailed algorithm of spglib is describted the following text:
For questions, bug reports, and comments, please visit following mailing list:
Spglib project acknowledges Paweł T. Jochym for deployment and packaging, Yusuke Seto for the Crystallographic database, and Dimitar Pashov for the fortran interface.