gr-owc is a GNU Radio Out-Of-Tree (OOT) module designed for Optical Wireless Communication (OWC). It provides a comprehensive suite of signal processing blocks designed to enable efficient experimentation, research, and development of optical wireless systems within the GNU Radio. The ‘gr-owc’ module covers OWC channel simulation, modulation and demodulation techniques, and other essential components. We describe how these blocks can also be implemented in physical systems using Software Defined Radio (SDR) hardware.