  We introduce an open-source package called QTraj that solves the Lindblad
equation for heavy-quarkonium dynamics using the quantum trajectories
algorithm. The package allows users to simulate the suppression of
heavy-quarkonium states using externally-supplied input from 3+1D hydrodynamics
simulations. The code uses a split-step pseudo-spectral method for updating the
wave-function between jumps, which is implemented using the open-source
multi-threaded FFTW3 package. This allows one to have manifestly unitary
evolution when using real-valued potentials. In this paper, we provide detailed
documentation of QTraj 1.0, installation instructions, and present various
tests and benchmarks of the code.
