CoREAS v1.4 is now available as an integral part of CORSIKA 7.74.
It mainly features improvements with regard to MPI parallelisation as well as simulation of radio emission from inclined air showers with zenith angles beyond 70°. In addition, a converter is now included to store CoREAS simulations output in HDF5 format, along with the calculation of high-level quantities such as energy fluences in the shower plane.
Please visit the CORSIKA webpage and download the code directly from there.
Information on how to use CoREAS is available from the CoREAS user's manual. Also, please check out this article with information on radio emission simulations with CoREAS.