Staff Software Engineer, Backend (Capacity Modeling)

Affirm is a financial technology company that provides transparent, pay-over-time solutions with no hidden fees or surprises. The Capacity Modeling team ensures Affirm can safely handle forecasted traffic, especially during peak sales events, by translating demand forecasts into concrete, testable capacity plans. They build and maintain statistical capacity models that map traffic inputs (e.g., checkout volume, app opens, batch/job activity) to resource outputs (CPU, memory, connections) and convert those forecasts into recommended capacity settings such as pod counts, HPA ranges, and infrastructure sizing changes across regions and environments. Coverage includes Compute, ElasticCache, DynamoDB, AuroraDB, and more.

• Set technical strategy for your team on a year-long time scale and tie it to critical, business-impacting projects.
• Collaborate across teams in the product development lifecycle with product management, design, and analytics to ensure technical sustainability, risks, and trade-offs are well understood and managed.
• Act as a force-multiplier through definition and advocacy of technical solutions and operational processes.
• Take ownership of your team's operations and availability by ensuring the right monitoring, triage rotations, playbooks, policies, testing, and alerting are in place to support on-call efforts.
• Foster a culture of quality and ownership by setting code review and design standards, and advocating for them through writing and tech talks.
• Help develop talent on your team by providing feedback and guidance, and leading by example.

• 8+ years of experience designing, developing, and launching backend systems at scale using languages like Python or Kotlin.
• Extensive track record of developing highly available distributed systems using technologies like AWS, MySQL, Spark, and Kubernetes.
• Experience supporting scale up and down of large-scale sales events such as Prime Day, Black Friday Cyber Monday, or other sales holidays.
• Experience tuning autoscaling, CPU/Memory, and multi-threading for compute-type workloads.
• Experience delivering major features, system components, or deprecating existing functionality through a technical and execution plan.
• Strong verbal and written communication skills for effective collaboration with a global engineering team.
• Equivalent practical experience or a Bachelor's degree in a related field.

Base pay is part of a total compensation package that may include equity rewards, monthly stipends for health, wellness, and tech spending, and benefits including 100% subsidized medical coverage, dental, and vision for you and your dependents. USA base pay range (CA, WA, NY, NJ, CT) per year: $230,000 - $290,000. USA base pay range (all other U.S. states) per year: $204,000 - $264,000.

Click the 'Submit Application' button on the job posting page to apply. Affirm is committed to providing an inclusive interview process, including accommodations for candidates with disabilities.