We present QuTiP (http://www.qutip.org), an object-oriented, open-source framework for solving the dynamics of open quantum systems. Written in Python, and using a combination of Cython, NumPy, SciPy, and matplotlib, QuTiP provides an environment for computational quantum mechanics that is both easy and efficient to use. Arbitrary quantum systems, including time-dependent systems, may be built up from operators and states defined by a quantum object class, and then passed on to a choice of unitary or dissipative evolution solvers. Here we give an overview of the basic structure for the framework, and the techniques used in its implementation. We also present a few selected examples from current research on quantum mechanics that illustrate the strengths of the framework, as well as the types of calculations that can be performed. This framework is particularly well suited to the fields of quantum optics, superconducting circuit devices, nanomechanics, and trapped ions, while also being ideal as an educational tool.
