I will describe three paths to categorification of RTW invariants of knots, and the relations between them. The first is based on a category of B type branes on resolutions of slices in affine Grassmannians, the second on a category of A-branes in the mirror Landau-Ginzburg theory. The third is the approach based on counting solutions to five dimensional
equations with gauge theory origin. All three approaches can be deduced starting from a string theory in six dimensions. This is based in joint works with Andrei Okounkov and with Dimitrii Galakhov.