The Sequential Quantum Gate Decomposer (SQUANDER) package provides a novel solution to decompose any n-qubit unitary into a sequence of one-qubit rotations and CNOT gates. SQUANDER utilizes a new gate synthesis technique that applies periodic layers of CNOTs and parametric one-qubit gates to an n-qubit unitary such that the resulting unitary is 1-qubit decoupled, i.e., is a tensor product of an (n-1)-qubit and a 1-qubit unitary. Related articles: [1] Péter Rakyta, Zoltán Zimborás, Approaching the theoretical limit in quantum gate decomposition, Quantum 6, 710 (2022). [2] Péter Rakyta, Zoltán Zimborás, Efficient quantum gate decomposition via adaptive circuit compression, arXiv:2203.04426. [3] Peter Rakyta, Gregory Morse, Jakab Nádori, Zita Majnay-Takács, Oskar Mencer, Zoltán Zimborás, Highly optimized quantum circuits synthesized via data-flow engines, arXiv:2211.07685