o80 (pronounced "oh-eighty") is software for synchronizing and organizing message exchange between (realtime) processes via simple customized Python APIs. Its target domain is robotics and machine learning. Our motivation for developing o80 is to ease the setup of robotics experiments (i.e., integration of various hardware and software) by machine learning scientists. Such setup typically requires time and technical effort, especially when realtime processes are involved. Ideally, scientists should have access to a simple Python API that hides the lower level communication details and simply allows the sending of actions and receiving of observations. o80 is a tool box for creating such API.