OLMoE, developed by Ai2, is an open-source language model application aimed at providing researchers and developers a fully open toolkit for conducting AI experiments on-device. The app supports offline operation on iPhone and iPad, ensuring complete privacy for user data. Built upon the efficient OLMoE model, it maintains high performance on mobile devices through optimization and quantization. The open-source nature of the application makes it a vital foundation for the research and development of the next generation of on-device AI applications.