Keep Our Communities Safe Act of 2023 This bill revises provisions related to the authority of the Department of Homeland Security (DHS) to detain non-U.S. nationals ( aliens under federal law). DHS may detain an individual pending a removal decision for any length of time until the individual is subject to a final removal order. DHS must detain certain individuals, such as those convicted of an aggravated felony, beyond certain time limits for immigration-related detention. The authority of the Department of Justice to review DHS custody decisions concerning an individual awaiting a removal decision shall be limited to whether the individual may be detained, released on bond, or released with no bond. DHS may release such an individual on bond only if the individual is not a flight risk or risk to the community. For an individual subject to a removal order, DHS may extend the 90-day removal period (generally the window in which DHS has to remove an individual after a final order of removal) in certain instances, such as when removal is stayed during an appeal. DHS may continue to detain an individual beyond the removal period and any removal period extensions. DHS must periodically certify a justification for detaining an individual beyond the removal period. DHS must establish a detention review process for individuals who (1) have made all reasonable efforts to comply with a removal order, and (2) are not subject to mandatory detention. DHS shall use this process to determine whether such an individual should be detained or released with conditions.