Oh One Pro is a Mac-based utility that converts PDF documents and source code to XML and images to process them using ChatGPT models, specifically O1-Pro and O3-Mini. Users can drag and drop files into the app, which converts documents into XML format for text extraction and analysis. The app features a native interface optimized for M1/M2 performance, supports light and dark themes, and processes all operations locally on the device, ensuring privacy without requiring an account.