Staff AI Engineer, Applied AI

<p>Block is one company built from many blocks, all united by the same purpose of economic empowerment. The blocks that form our foundational teams — People, Finance, Counsel, Hardware, Information Security, Platform Infrastructure Engineering, and more — provide support and guidance at the corporate level. They work across business groups and around the globe, spanning time zones and disciplines to develop inclusive People policies, forecast finances, give legal counsel, safeguard systems, nurture new initiatives, and more. Every challenge creates possibilities, and we need different perspectives to see them all. Bring yours to Block.</p> <p><strong>The Role</strong></p> <p>We are looking for proactive builders to develop agentic AI products for Square and Cash App. Your role is to move beyond passive chatbots and build systems that take autonomous action to solve problems for our merchants and customers.</p> <p>We want engineers who are obsessed with applying machine learning to the real world rather than theoretical research. You will own the full lifecycle of products, from the first line of code to strategic impact. Your goal is to deliver immediate, tangible value to small businesses and individual consumers through intelligent proactive automation.</p> <p>You will partner across Block to deliver highly visible solutions, identifying new possibilities for agentic workflows and driving product direction. As a lead in this space, you will stay at the forefront of AI advancements to ensure our products remain innovative, effective, and reliable. To scale the quality of these experiences, you will implement reinforcement learning systems to refine agent behavior using state-of-the-art techniques.</p> <p>This is a unique opportunity to become a leading expert in AI at Block. You'll work on projects that transform the way we build products and serve our customers. We welcome individuals who are passionate about building for the real world, embracing pragmatic approaches, and seeing challenges from fresh, nontraditional viewpoints.</p> <p><strong>You Will</strong></p> <ul> <li>Partner across Block to identify new agentic workflows and drive product direction, staying at the forefront of AI advancements to ensure our solutions remain effective and innovative.</li> <li>Build and deploy production-ready, LLM-powered systems including autonomous agents and tool-use capabilities working directly with foundation model APIs.</li> <li>Design rigorous evaluation frameworks and custom metrics from scratch to diagnose system performance and ensure agentic products work reliably for Square merchants and Cash App customers.</li> <li>Apply a solid grasp of concepts like overfitting, generalization, and data quality to reason about model behavior and identify the right technical levers to pull when a system underperforms.</li> <li>Build automated feedback pipelines and reward models to scale the quality of our experiences, implementing state-of-the-art reinforcement learning techniques to refine agent behavior over time.</li> <li>Own the full product lifecycle by contributing across the stack—from backend APIs and data pipelines to frontend integration—to deliver immediate, proactive value to our users.</li> </ul> <p><strong>You Have</strong></p> <ul> <li>12+ years of experience in training and deploying ML models, developing ML software, and shipping customer-facing ML products.</li> <li>Deep understanding of modern ML techniques (e.g. Large Language Models) and the ML lifecycle from data gathering, training, model evaluation, MLOps, and productionizing models.</li> <li>Ruthless pragmatism when solving new and unconventional problems</li> <li>A desire to understand our clients' needs in order to design tools and systems that solve our customer's problems. As a platform team, our main customers are internal developers and products.</li> <li>Ability to produce production-quality code and services incorporating testing, evaluation, monitoring a ... (truncated, view full listing at source)