Dark sectors are a very motivated target in the search for physics beyond the standard model and appear in many models of dark matter which explain the observed abundance. Due to their small couplings, dark sectors require new experimental strategies in order to be studied. In this talk I will present new ways to detect dark sectors through transient visible signals following a neutron star merger. Focusing on the visibly decaying dark photon scenario, I will show that the merger remnant can produce a very large flux of dark photons, and explore the visible signatures coming from their decays. The most promising signal is a bright and short burst of MeV photons produced by the decay products. This can be used to probe a large portion of unexplored parameter space, including much of the unconstrained parameter space for freeze-in dark matter models with interactions mediated by the dark photon.