As Mathematica has most necessary matrix algebra functions (crucially the matrix exponential) built in natively (both for symbolic and numerics) it is quite simple to roll most things yourself. For more complicated manipulations QuantumUtils is useful (disclaimer this was made by some colleagues).
I should point out that the focus of this library is not on building and simulating algorithms (although possible) but the description and manipulation of quantum channels and hamiltonians. Hamiltonian simulation and GRAPE pulse design is also baked in.