An AssImp (short for Open Asset Import Library) developer primarily works on integrating, maintaining, and enhancing the open-source library that's designed to import model files into applications. They handle various file formats like .obj, .fbx, ., and more. Their tasks include fixing bugs, improving performance, and adding new features to ensure the library supports as many formats as possible. They also collaborate with other developers, understanding their needs and translating them into code. Their goal is to provide a reliable, efficient, and easy-to-use import infrastructure for models, contributing to the broader development community.