This is a new release of the CANOPS model for examining the evolution and stability of O2 levels in the ocean-atmosphere system. The results are submitted to Geoscientific Model Development. The basic design of the model is based on the CANOPS model that is originally developed by Ozaki and Tajika (2013) EPSL and Ozaki et al. (2019) Geobiology. The reader should consult these papers for a comprehensive explanation and empirical/theoretical basis. The model's framework was expanded for this study by including (1) mass balance calculation of O2 in the atmosphere, (2) mass balance calculation of sedimentary reservoirs, and (3) simplified global redox (O2) budget. This model is still undergoing regular development and it is recommended that potential users contact the corresponding author (Kazumi Ozaki; kazumi.ozaki@sci.toho-u.ac.jp) to obtain the latest version. This code is provided freely but with the requirement that prospective users contact the corresponding author with their research plans to avoid parallel projects emerging.