[Remote] Senior Machine Learning Engineer II, Search & Recommendations Ranking

Note: The job is a remote job and is open to candidates in USA. Instacart is transforming the grocery industry by providing essential services for grocery delivery. The Senior Machine Learning Engineer II will architect and develop advanced ranking systems that enhance query understanding and personalization across search and recommendations.ResponsibilitiesArchitect the ranking backbone that unifies query understanding, personalization, multi-objective ranking, ads, and merchandising into a single adaptive platformDesign and build a search autosuggest system optimized for personalization and value-based relevanceDesign long-horizon objective functions (e.g., incrementality, LTV, habit formation) and build uplift/causal value models that move beyond short-term engagementDevelop production-grade Multi-Task Learning (e.g., shared encoders, MMOE/PLE task heads) to jointly learn relevance, propensity, margin, and churn risk—ensuring calibration, constraints, and explainabilityOwn the inference layer: goal-aware re-rankers, diversity and quality constraints, safe exploration, and millisecond-class latency optimizationAdvance evaluation practices: online experiments, long-horizon cohort metrics, counterfactual evaluations, and attribution pipelines for tracking incremental GTV and retentionPartner across ads, infrastructure, product, and design teams to translate business goals into ranking policies and measurable ROIMentor ML engineers to build expertise in ranking, causal inference, and scalable serving systemsSkills5+ years applying ML at scale (3+ years in technical leadership), with a proven track record improving ranking or recommendation systems in productionDemonstrated success in applying multi-objective or constrained optimization to balance relevance, revenue, margin, and user experience; experience with online testing and attribution beyond CTRStrong coding (Python) and data fluency (SQL/Pandas), with expertise in classic ML techniques (e.g., XGBoost) and deep learning frameworks (TensorFlow/PyTorch)Excellent analytical skills and strong cross-functional communication abilitiesExpertise in multi-task learning architectures (e.g., MMOE/PLE, shared encoders), calibration, counterfactual evaluation, uplift/causal modeling, and/or contextual bandits for explorationExperience building low-latency ranking services, including feature stores, caching, vector + lexical retrieval, re-ranking, and A/B testing infrastructure, with expertise in constraint-aware inferenceHands-on experience with LLMs as feature/recall enhancers (e.g., embeddings, adapter tuning) while maintaining clarity on when the ranker should arbitrateBenefitsInstacart provides highly market-competitive compensation and benefits in each location where our employees work.This role is eligible for a new hire equity grant as well as annual refresh grants.Please read more about our benefits offerings here.Company OverviewInstacart is an online grocery platform that offers same-day delivery and pickup services for retailers and consumers. It was founded in 2012, and is headquartered in San Francisco, California, USA, with a workforce of 1001-5000 employees. Its website is https://www.instacart.com.Company H1B SponsorshipInstacart has a track record of offering H1B sponsorships, with 23 in 2026, 152 in 2025, 173 in 2024, 109 in 2023, 159 in 2022, 170 in 2021, 59 in 2020. Please note that this does not guarantee sponsorship for this specific role.