StochasticGW is a free software package for GW calculations of very large systems, potentially tens of thousands of electrons and more. The method and its applications, and specifically a manual, are described in www.stochasticGW.com
The source code for StochasticGW is available from GitHub, see https://github.com/stochasticGW/stochasticGW
An example wavefunction file (very large, almost 1Gbyte, beware!) needed for the simulation of C60 in the stochasticGW manual (see the manual for details) is available: wf.bin.gz
The beta version of StochasticGW was just delivered (May 2018)!
StochasticGW is a post-DFT approach, requiring, in the present version (v1.0), the DFT occupied wavefunctions and coordinates.