  Quantum circuits constructed from Josephson junctions and superconducting
electronics are key to many quantum computing and quantum optics applications.
Designing these circuits involves calculating the Hamiltonian describing their
quantum behavior. Here we present QuCAT, or "Quantum Circuit Analyzer Tool", an
open-source framework to help in this task. This open-source Python library
features an intuitive graphical or programmatical interface to create circuits,
the ability to compute their Hamiltonian, and a set of complimentary
functionalities such as calculating dissipation rates or visualizing current
flow in the circuit.
