Hi, I’m Xuewen 👋

I’m a Senior Staff Machine Learning Engineer at Coupang, where I lead teams building large language models, multimodal systems, and search experiences that serve millions of users. My work focuses on LLM pretraining and post-training (instruction tuning, DPO, GRPO), multimodal learning, search and recommendation, and ads quality. I led the end-to-end development of CoupangGPT and CoupangGPT-VL, as well as OGPT at OPPO — company-wide language models adopted across search, catalog, ads, and on-device assistants. I hold a Ph.D. from Stony Brook University in multimodal learning and NLP. I’ve reviewed 200+ papers for venues like NeurIPS, ACL, EMNLP, CVPR, and TPAMI, and contribute to open-source projects such as Axolotl and ms-swift. This site is where I share notes, blog posts, publications, and projects.