Together Custom Models is an end-to-end solution for building powerful LLMs from data design to evaluation, providing a state-of-the-art cluster with NVIDIA H100 and A100 GPUs, and a team of expert researchers available to work with customers every step of the way. The models built with Together Custom Models are owned by the customer, allowing for full ownership, control, and customization. The solution includes stages such as data discovery & optimization, selecting model architecture, hyperparameters, and training strategy, training, tuning & alignment, and evaluation. It leverages state-of-the-art techniques like DSIR, DoReMi, FlashAttention-2, and CocktailSGD to achieve fast and reliable performance. With Together Custom Models, customers can build custom models that are tailored to their specific needs, resulting in higher accuracy and adaptability to their tasks, with the best price-performance tradeoff for production applications.