Abstract: Link homology is the space of states of BPS particles in a special 5d QFT. The BPS particles can be presented as D2 branes attached to Chern-Simons-related D4 branes and link-related NS5 branes. We assume that D2 branes form a stack split into domains by D4 and NS5 interfaces. The vibrations of the stack are described by a 3d topological B-model with target spaces being Nakajima quiver varieties. We use the associated 2-categories in order to describe the categorical braid group actions and find the link homology. The talk is based on my joint work with A.Oblomkov, R.Rimanyi and T.Dimofte.