  We present a numerically exact steady-state inchworm Monte Carlo method for
nonequilibrium quantum impurity models. Rather than propagating an initial
state to long times, the method is directly formulated in the steady-state.
This eliminates any need to traverse the transient dynamics and grants access
to a much larger range of parameter regimes at vastly reduced computational
costs. We benchmark the method on equilibrium Green's functions of quantum dots
in the noninteracting limit and in the unitary limit of the Kondo regime. We
then consider correlated materials described with dynamical mean field theory
and driven away from equilibrium by a bias voltage. We show that the response
of a correlated material to a bias voltage differs qualitatively from the
splitting of the Kondo resonance observed in bias-driven quantum dots.
