As a Senior Applied Scientist on the Siri team, you will play a crucial role in developing powerful large language models (LLMs) that enhance user interactions with Apple devices. This position focuses on driving the design, development, and delivery of LLMs that enable personalized and efficient experiences. You will work closely with researchers and engineers to transition innovations from prototype to production, emphasizing hands-on technical leadership and rapid iteration. The ideal candidate will have a strong background in applied research and a passion for delivering impactful results.

• Masters or PhD in Computer Science, Machine Learning Engineering or equivalent professional experience
• 5+ years of hands-on industry experience with a proven track record of shipping ML-powered products or features, ideally involving LLMs
• Deep expertise in LLM/VLM post-training methods, including supervised fine-tuning, preference optimization methods and reinforcement learning
• Proficiency in Python and one of the deep learning frameworks such as PyTorch, JAX, or TensorFlow
• Excellent communication skills, including strong interpersonal, verbal and written abilities
• Experience developing AI agents capable of complex reasoning, planning, tool use and UI control in diverse environments
• Experience developing small LLMs for constrained or edge devices
• Deep understanding of model efficiency and deployment trade-offs in production environments
• Experience with multi-modal foundation models
• Experience developing ML systems for natural language understanding or digital assistants

• Drive the design, development and delivery of large language models that power Siri
• Lead research and engineering efforts in model post-training techniques
• Collaborate closely with researchers, software engineers and product teams
• Identify and apply post-training techniques to advance model efficiency
• Contribute to the end-to-end model lifecycle process
• Set technical directions for the team and emphasize hands-on innovation
• Deliver impactful results through rapid iteration

• Employees at Apple are often offered comprehensive benefits that support physical and mental well-being—flexible medical plans, confidential counseling, onsite wellness centers at major campuses, and resources for fitness and daily life. Families typically receive fertility support, paid parental leave with gradual return, caregiving leave, and dependent-care guidance, while financial perks commonly include stock grants (with purchase discounts), 401(k) matching, and income-protection coverage. Employees also see robust time off, Apple University learning and tuition reimbursement, donation matching and paid volunteer hours, and deep product and partner discounts.