Senior Machine Learning Engineer II, Search & Recommendations Ranking

<div class="content-intro"><p><strong>We're transforming the grocery industry</strong></p> <p><span class="im">At Instacart, we invite the world to share love through food because we believe everyone should have access to the food they love and more time to enjoy it together. Where others see a simple need for grocery delivery, we see exciting complexity and endless opportunity to serve the varied needs of our community. We work to deliver an essential service that customers rely on to get their groceries and household goods, while also offering safe and flexible earnings opportunities to Instacart Personal Shoppers.</span></p> <p>Instacart has become a lifeline for millions of people, and we’re building the team to help push our shopping cart forward. If you’re ready to do the best work of your life, come join our table.</p> <p><strong>Instacart is a Flex First team </strong></p> <p>There’s no one-size fits all approach to how we do our best work. Our employees have the flexibility to choose where they do their best work—whether it’s from home, an office, or your favorite coffee shop—while staying connected and building community through regular in-person events. <a href="https://www.instacart.careers/flex-first" target="_blank" data-saferedirecturl="https://www.google.com/url?q=https://instacart.careers/remote/&amp;source=gmail&amp;ust=1651869232122000&amp;usg=AOvVaw37OlxP8hAKN7nq4YwHQH7e">Learn more about our flexible approach to where we work.</a></p></div><p>Overview</p> <p>The Search &amp; Personalization ML team is Instacart’s engine for state-of-the-art multi-task, multi-objective ranking—unifying search, discovery, recommendation, ads, and merchandising into a single value-aware platform. Partnering with world-class engineers, scientists, and PMs, we build the ranking backbone that powers every pixel of the shopping journey, optimizing not just for clicks, but for incremental GTV, basket lift, and retention over the long run.</p> <p>What We’re Building</p> <ul> <li>Foundational Ranking Backbone Models: Multi-task/multi-objective models (shared encoders + task heads) that jointly learn relevance, conversion, margin contribution, churn risk, and ad quality, enabling consistent decisions across search and recommendations.</li> <li>Value-Aware Optimization: Uplift and long-horizon value models that steer decisions toward incrementality and LTV, with calibrated constraints on quality, diversity, fairness, and spend pacing—plus guardrails for safe exploration.</li> <li>LLM-Enhanced Retrieval &amp; Features: Using LLMs to enrich query and item semantics for long-tail recall, generate features for cold-starts, and feed the ranker with reasoning-rich context, while remaining the source