We review the recent programme initiated by Eberhardt, Gaberdiel and Gopakumar, which relates the superstring perturbation theory on ${\rm AdS}_3\times {\rm S_3}\times \mathbb{T}^4$ with one unit of NSNS flux to the Lunin-Mathur construction of the correlators in the symmetric product orbifold of a 4-torus CFT. We extend their result to a non-perturbative regime by considering various types of D-branes in the bulk and finding their holographic duals in the boundary CFT.