Senior Software Engineer, Developer Experience

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. About the role More and more of our engineering work now runs through autonomous agents, and those agents can only be as effective as the tools, context, and codebase around them. As a Developer Experience Engineer, you'll build the tooling and agent workflows that let humans and agents change our largest monorepos quickly and safely. You'll own the interfaces engineers use to observe, steer, and give context to the agents working on our code. You'll also build the guardrails that keep complexity in check as those agents take on bigger changes. Large-scale work like framework upgrades, language migrations, and dependency health is still part of the job, but you'll do it by building and steering agents rather than making the changes by hand. This is a high-leverage role. Every improvement you ship multiplies across the whole engineering organization. What you’ll do • Build and ship the tools engineers and their agents use every day, such as CLIs, desktop integrations, and interfaces for observing, unblocking, and steering autonomous agents, and own their adoption, distribution, and support • Design and evolve agentic loops (the plan, act, verify, and iterate cycles) and the harnesses, skills, and context that let agents do real engineering work reliably • Build agent workflows that drive large-scale changes across the codebase, including framework upgrades, language migrations, and dependency updates, with minimal disruption to product teams • Build the guardrails, tests, and automation that make large, agent-authored changes safe to land, and track the leading indicators of growing complexity • Find friction in the development workflow for both humans and agents, and fix the root causes • Partner with builders inside and outside of engineering to understand their pain points, and measure the adoption and impact of what you ship • Set technical direction and mentor other engineers on agent design, tooling, and codebase health What we’re looking for We care more about what you've done than about which specific technologies you used to do it. Required • Shipping developer tooling at scale: You've shipped tools that engineers use daily, such as CLIs, desktop integrations, configuration management, or internal platforms. You understand what it takes to drive adoption, debug problems, and support users. • Scaling work with agents: You've built agent workflows that finished work that would normally take a team weeks. Examples include generating codebase summaries or world models, writing skills and loops, or orchestrating a team of semi-deterministic agents. You have a deep understanding of agentic loops (tool use, context management, verification, failure handling) and are eager to keep evolving them as the field changes. • Evolving frameworks and large codebases: You have deep experience with application or platform frameworks, including upgrading them and managing their evolution over time. You also have a track record of leading migrations or large refactors from planning through rollout. • Significant experience (typically 10+ years for Staff, 7+ for Senior) working in large, complex co