qsim is a full wavefunction simulator that has been optimized to support vectorized operations and multi-threading.
qsimh is a hybrid Schrödinger-Feynman simulator. It simulates separate disjoint sets of qubit using a full wave vector simulator, and then uses Feynman paths to sum over gates that span the sets.
Cirq is a python framework for writing, simulating, and executing quantum programs. Cirq’s built in simulator is useful to around 20 qubits. By using the qsim Cirq simulator one can boost the number of qubits simulated to be mostly limited by available ram. Up to 40 qubits can be simulated on a 90 core Intel Xeon workstation.
Learn how to simulate up to 38 qubits on Google Cloud’s Compute Engine. qsim has a prepackaged docker image that allows easy deployment of qsim, Juypter, and Cirq onto a virtual machine.