*Abstract:* In the first part of the talk, a relative version of the Chas-Sullivan string topology operations is used to construct a knot invariant known as Lenny Ng's cord algebra. This invariant distinguishes the unknot from all nontrivial knots, and it contains some classical knot invariants such as the Alexander polynomial.In the second part of the talk, I will show that the cord algebra agrees with a holomorphic curve invariant, the Legendrian contact homology of the unit conormal bundle.