Senior Machine Learning Engineer, E-Commerce

About the Team:
Global E-commerce is a content-driven business powered by short-form video and live-streaming, dedicated to becoming the premier destination for users to discover affordable, high-quality products. Our team strives to deliver a tailored and efficient shopping experience while upholding a robust governance and risk control framework to ensure platform integrity, merchant compliance, and a secure ecosystem.

• Architect and develop sophisticated LLM-based systems to process high-dimensional unstructured data (e.g., text, logs, conversations) from diverse sources.
• Define and implement complex semantic understanding frameworks, including fine-grained intent classification and entity extraction, to achieve deep contextual awareness.
• Apply state-of-the-art techniques to enhance model performance, including Instruction Tuning, RLHF/DPO, and Contextual Prompt Engineering.
• Optimize model serving for production environments using quantization, distillation, and efficient attention mechanisms (e.g., Flash Attention, vLLM).

Minimum Qualifications:

• MS or PhD in Computer Science, AI, Mathematics, or a related field.
• 5+ years of professional experience in one or more of the following fields:
  Machine Learning, Natural Language Processing (NLP), or Computer Vision.
• Proficiency in software development with at least one of the following programming languages: C++, Python, Go, or Java.

Preferred Qualifications:

• Experience in fine-tuning, distillation, or reinforcement learning for large language models in conversational AI applications.
• Proficiency in multilingual NLP, machine translation, and cross-lingual dialogue modeling.
• Experience in developing and optimizing e-commerce video and product multimodal large models, combining LLMs with video/product representations to support tasks like multimodal classification, video QA, and cross-modal retrieval.
• A strong understanding of e-commerce policies, dispute resolution workflows, and merchant-buyer interactions to inform AI service design.

Tik Tok USDS Joint Venture LLC is dedicated to the safety and security of millions of Americans who create, discover, and connect with what they love on the apps we operate. The Joint Venture has been established in compliance with the Executive Order signed by President Trump on September 25, 2025. Our foundation is a comprehensive data privacy and cybersecurity program we operate under defined safeguards to protect national security and secure U.S. user data, apps and the algorithm.

We safeguard the U.S. content ecosystem, holding decision-making authority for trust and safety policies and moderation. USDS Joint Venture helps ensure Americans can continue to express their creativity, discover new hobbies and interests, and build thriving communities and businesses on a global scale.

On-site presence across teams allows the company to operate with greater speed, alignment, and agility — especially in areas like real-time decision-making, team development, and integrated execution. As such, the company is shifting from a hybrid work model to a fully in-person schedule up to 5 days a week.

Inspiring creativity is at the core of Tik Tok's mission. Our innovative product is built to help people authentically express themselves, discover and connect – and our global, diverse teams make that possible. Together, we create value for our communities, inspire creativity and bring joy - a mission we work towards every day.

We strive to do great things with great people. We lead with curiosity, humility, and a desire to make impact in a rapidly growing tech company. Every challenge is an opportunity to learn and innovate as one team. We're resilient and embrace challenges as they…