Quantum software includes programming frameworks, simulators, and transpilers for quantum algorithms. Libraries provide circuit builders (Qiskit, CUDA-Q), simulators for ~20 qubits (cuStateVec, QuTiP), and compilation to hardware-native gate sets. Research tools (scqubits, QuTiP) focus on open quantum systems; production frameworks emphasize variational algorithms (VQE, QAOA) with classical optimization loops. Most frameworks are Python-based with GPU acceleration available (CUDA-Q, cuQuantum).