| [pydot](https://pypi.python.org/pypi/pydot) | A Python interface to GraphViz and the DOT language. |
| [pyFFTW](https://pypi.python.org/pypi/pyFFTW) | A pythonic wrapper around FFTW, the FFT library, presenting a unified interface for all the supported transforms. |
| [pymatgen](https://pypi.python.org/pypi/pymatgen) | Python Materials Genomics is a robust materials analysis code that defines core object representations for structures and molecules with support for many electronic structure codes. It is currently the core analysis code powering the Materials Project (https://www.materialsproject.org). |
| [PyNaCl](https://pypi.python.org/pypi/PyNaCl) | Python binding to the Networking and Cryptography (NaCl) library |
| [pyparsing](http://pyparsing.wikispaces.com) | The pyparsing module provides a library of classes that client code uses to construct the grammar directly in Python code. |
| PyQt | |
| [PyQt5](http://www.riverbankcomputing.co.uk/software/pyqt) | PyQt5 is a set of Python bindings for v5 of the Qt application framework from The Qt Company. |