  This paper puts the theory of quasi-Hamiltonian reduction in the framework of
shifted symplectic structures developed by Pantev, To\"{e}n, Vaqui\'{e} and
Vezzosi. We compute the symplectic structures on mapping stacks and show how
the AKSZ topological field theory defined by Calaque allows one to neatly
package the constructions used in quasi-Hamiltonian reduction. Finally, we
explain how a prequantization of character stacks can be obtained purely
locally.
