Principal Engineer

Who you are

• 15+ years of industry experience in large-scale systems and/or machine learning, with a track record of impact in search, recommendations, feeds, or conversational AI
• Proven experience as a Principal Engineer, Architect, or equivalent senior technical leader driving cross‑org technical strategy and execution
• Deep expertise in at least two of the following, and strong familiarity with the others:
• Large-scale retrieval and ranking (e.g., learning-to-rank, multi-task and multi-objective optimization, bandits, RL for recommendations)
• Representation learning (e.g., embeddings, multi-modal models, dense and sparse retrieval)
• Search systems (indexing, query understanding, relevance tuning, latency/throughput optimization)
• Large language models and generative AI (prompting, fine-tuning, RAG, agents, safety/guardrails, evaluation)
• Demonstrated ability to define and drive multi-year architectural transformations at scale (e.g., re-architecting a core ranking stack, unifying feature platforms, evolving legacy systems to modern ML platforms)
• Strong product intuition and experience partnering with PM/Design/Data Science on ambiguous, 0→1 and 1→N product bets
• Exceptional communication skills: able to crisply articulate strategy, tradeoffs, and technical direction to executives, peers, and broad engineering audiences
• Passion for mentoring and growing senior/staff engineers; history of building strong engineering cultures and communities of practice
• Bachelor’s degree in computer science, a related field or equivalent experience
• Prior experience in consumer discovery products at global scale (e.g., feeds, search, recommendations, marketplaces, or assistants)
• Experience building or integrating AI assistants or agentic workflows into consumer experiences

What the job involves

• We’re looking for a Principal Engineer to set the technical vision and lead foundational work across Homefeed, Search, and our emerging AI Assistant experiences at Pinterest
• This role sits at the intersection of relevance, ranking, retrieval, and generative AI, and will shape how hundreds of millions of Pinners discover and act on inspiration every day
• You will operate as a cross-cutting technical leader: defining long-term architecture, raising the bar on ML and systems excellence, and partnering closely with product and executive leadership to drive step‑function improvements in engagement, quality, and creator value
• Define the long-term technical strategy and architecture for Homefeed, Search, and AI Assistant, including retrieval, ranking, personalization, and generative experiences
• Drive a multi‑year roadmap for unifying signals, features, and models across surfaces to deliver a coherent, high-quality discovery experience
• Lead the design and adoption of large-scale retrieval and ranking systems (e.g., multi-stage retrieval, representation learning, multi-objective optimization) that materially improve relevance and monetization
• Architect how LLMs and foundation models integrate with our core discovery stack (e.g., query understanding, intent modeling, content understanding, conversation orchestration, safety/guardrails)
• Set technical direction for experimentation, measurement, and evaluation frameworks, including offline metrics, online experimentation, and causal inference for discovery and generative use cases
• Provide hands-on technical leadership on a small number of high-leverage projects: design critical components, review designs/PRs, de-risk complex launches, and mentor senior engineers and staff+ TLs
• Partner deeply with Product, Data Science, Research, and Design to frame the right problems, translate product bets into robust technical plans, and ensure we are solving for long-term platform health, not just short-term metrics
• Raise the bar for engineering excellence: reliability, performance, security/privacy, cost efficiency, and operational health of large-scale ML systems
• Represent Pinterest externally for these domains (e.g., talks, publications, partnerships) and help attract and grow top talent
• You will report into Pinterest’s Core Engineering leadership and work horizontally across multiple product and platform teams responsible for Homefeed, Search, and AI Assistant
• You will spend a meaningful portion of your time on hands-on technical work (design, reviews, prototyping) while also driving long-term strategy, standards, and alignment across organizations
• You will be measured on durable technical impact: system-level improvements, model and product outcomes, reduction in complexity and operational risk, and the growth of leaders and capabilities around you