Microsoft Quantum Development Kit
Microsoft recently introduced a software platform for simulating quantum computers, the Microsoft Quantum Development Kit, based on their new programming language Q# (Q-Sharp). This was initially implemented on Windows, and now versions are available for Mac and Linux operating systems. It is now also compatible with the Python language.
This platform is able to simulate up to about 30 logical qubits on a typical laptop computer, and will help users develop and debug applications that can be tested later on quantum computing hardware.
This development kit is available as a free download from Microsoft here.
For an overview of developing applications, see here.