Today's LLM (pre-) training and research workflows typically allocate a significant amount of compute to large-scale ablation studies. Despite the substantial compute costs of these ablations, existing open-source frameworks provide limited tooling for these experiments, often forcing researchers to write their own wrappers and scripts. We propose Modalities, an end-to-end PyTorch-native framework that integrates data-driven LLM research with large-scale model training from two angles. Firstly, by integrating state-of-the-art parallelization strategies, it enables both efficient pretraining and systematic ablations at trillion-token and billion-parameter scale. Secondly, Modalities adopts modular design with declarative, self-contained configuration, enabling reproducibility and extensibility levels that are difficult to achieve out-of-the-box with existing LLM training frameworks.
@article{arxiv.2602.08387,
title = {Modalities, a PyTorch-native Framework For Large-scale LLM Training and Research},
author = {Max Lübbering and Timm Ruland and Richard Rutmann and Felix Stollenwerk and David Fitzek and Michael Fromm and Alexander Weber and Rafet Sifa and Nicolas Flores-Herr and Joachim Köhler and Mehdi Ali},
journal= {arXiv preprint arXiv:2602.08387},
year = {2026}
}