The microstate structure of AdS3 black holes involves stringy ingredients, yet quantitative control over these ingredients in a regime where the state being described approximates a black hole has been elusive. This talk will show how 2d worldsheet current algebra provides a tool to describe the stringy objects that govern the black hole phase transition in AdS3 and linear dilaton backgrounds, providing a bridge between the entropy-carrying degrees of freedom of the dual non-gravitational theory (little strings or long strings) and their conjectured gravitational dual, the fuzzball.