Machine Learning Engineer - LLMs, Agent Systems, and Simulation Tooling, Siri Core Modeling

Apple’s Siri organization is hiring a Senior Machine Learning Engineer to advance scalable LLM reasoning systems and agent-based simulation and evaluation tooling for agentic voice experiences. The role spans infrastructure for training and experimentation, alongside integration of agent behaviors across client and backend environments.

• Define how next-generation intelligent agents reason, plan, and interact with people through natural voice and multimodal experiences
• Develop foundations for scalable LLM reasoning systems that support human-AI interaction
• Build core reasoning and simulation capabilities for a future agentic voice platform
• Advance approaches for how LLMs plan, adapt, and evaluate actions in realistic environments
• Contribute to reliable and trustworthy AI agents through robust infrastructure and tooling
• Design and run experiments in simulated environments and build scalable evaluation pipelines
• Integrate agent behaviors across client-side and backend systems
• Collaborate with ML scientists, applied researchers, and product engineers to transition early research into deployable systems
• Support development of a platform enabling developers and end-users to build rich, voice-driven AI experiences

• Design and implement scalable simulation and evaluation frameworks for LLM-based agents
• Translate novel reasoning approaches from ML researchers into production-grade systems
• Develop infrastructure for training and experimentation with agentic behaviors
• Integrate agent reasoning capabilities into both client-side and backend environments
• Improve iteration speed by creating tooling for experimentation, prototyping, and deployment

• Experience deploying LLM models in research or production contexts
• Knowledge of adaptive feedback loops, reinforcement learning, or interactive agent design
• Familiarity with client-backend integration for AI-driven applications
• MS or PhD in Computer Science, Machine Learning, or a related field
• Bachelor’s degree in Computer Science, Machine Learning, or related quantitative field, with 3+ years of relevant industry experience
• Strong skills in Python (preferred) and at least one other programming language
• Proven ML engineering experience, including system design, training pipelines, and deployment workflows
• Deep understanding of agent-based simulation, agentic RAG systems, and LLM evaluation methodologies
• Ability to balance long-term platform vision with pragmatic short-term delivery in fast-paced environments

• Python
• Reinforcement learning
• Agentic RAG systems
• LLM evaluation methodologies

• Location: Cupertino, CA (onsite)
• Experience Level: 3+ years
• Education: Bachelor’s degree in Computer Science, Machine Learning, or related quantitative field
• Salary: USD 150, per year

• Comprehensive medical and dental coverage
• Retirement benefits
• Discounted products and free services
• Reimbursement for certain educational expenses, including tuition
• Opportunity to become an Apple shareholder through participation in Apple’s discretionary employee stock programs
• Eligibility for discretionary restricted stock unit awards
• Can purchase Apple stock at a discount if voluntarily participating in Apple’s Employee Stock Purchase Plan
• Additionally, the role might be eligible for discretionary bonuses or commission payments as well as relocation
• Note:
  
  Apple benefit, compensation and employee stock programs are subject to eligibility requirements and other terms of the applicable plan or program