I will review how integrability can be used to understand the spectral
problem (including massless modes) of Type IIB string theory on AdS3 x S3 x T4 with
R-R flux. I will then show how integrability emerges in the dual CFT2. This provides
arguably the first non-BPS test of the planar AdS3/CFT2 correspondence in the
literature and gives strong evidence in identifying particular points in the moduli
space of the dual theories.