Staff Software Engineer, Backend (Observability)

At Affirm, we exist for the moments that matter—giving people a clear, predictable way to pay over time, with no hidden fees, no surprises, and no tradeoffs on what matters most. The Observability team builds the platform every Affirm engineer relies on to understand the behavior and performance of our systems. Our platform ingests 200+ TB/day of metrics, logs, and traces from hundreds of services across 80+ Kubernetes clusters, and when a user's checkout fails, our data is how engineers find out why. Over the next year, we’re moving to wide events, with one context-rich event per request, improving the signal-to-noise ratio to make debugging faster. We’re also introducing log sampling and building observability best practices into agentic development and code review, so that AI-assisted code is well instrumented by default. We’re looking for a Staff Software Engineer to be the technical lead for Observability. You’ll spend most of your time hands-on while defining the roadmap, driving cross-functional projects, mentoring a team of six engineers, and partnering closely with infrastructure and product teams. What You'll Do · You will own the architecture of Affirm’s telemetry pipeline, balancing reliability, query performance, and cost at 200+ TB/day. · You will design log sampling strategies that significantly reduce volume and cost without losing the signal engineers need during incidents. · You will shape how observability fits into agentic development, so that AI coding agents and code review catch instrumentation gaps before code ships. · You will be responsible for setting technical strategy for your team on a year-long time scale, and help your team tie it together with critical, business-impacting projects. · You will collaborate across teams in the product development lifecycle by collaborating with product management, design & analytics to ensure technical sustainability, risks and trade-offs are well understood and managed. · You will act as a force-multiplier for your team through your definition and advocacy of technical solutions and operational processes. · You take ownership of your team’s operations and availability by ensuring you have the right monitoring, triage rotations, playbooks, polcities, testing and alerting in place to support “keep the lights on” & on-call efforts. · You will foster a culture of quality and ownership on your team by setting code review and design standards for your team, and advocating for them beyond your team through your writing and tech talks. · You will help develop talent on your team by providing feedback and guidance, and leading by example. What We Look For · You have 8+ years of experience designing, developing and launching backend systems at scale using languages like Python or Kotlin. · You have an extensive track record of developing highly available distributed systems using technologies like AWS, MySQL, Flink and Kubernetes. · You have built or operated high-volume telemetry systems (metrics, logs, and/or traces) using technologies like OpenTelemetry, Kafka, and Terraform. · You have a well-informed point of view on modern observability practices such as structured and wide events, sampling, cardinality management, and SLOs. · You have driven adoption of a platform standard across many engineering teams, through both tooling and engagement. · You have experience delivering major features, system components or deprecating existing functionality in a system through the definition of a technical and execution plan. You write high quality code that is easily understood and used by others. · You thrive in ambiguity, and are comfortable moving from low level language idioms all the way to the architecture of large systems to understand how they work. · Your growth and im