Staff Software Engineer, Backend (Capacity Modeling)

About the role

Affirm is looking for a Staff Software Engineer to lead the Capacity Modeling team. You will shape technical strategy, ensure the platform can handle peak traffic, and drive high‑impact projects that keep the service reliable and scalable.

Key responsibilities

• Define and execute a multi‑year technical strategy for capacity planning.
• Collaborate with product, design, and analytics to manage technical risks and trade‑offs.
• Champion robust operational processes, including monitoring, alerting, on‑call rotations, and playbooks.
• Set and evangelize code review and design standards across the organization.
• Mentor engineers, provide feedback, and foster a culture of ownership and quality.

Required profile

• 8+ years of experience building backend systems at scale using Python or Kotlin.
• Proven track record with highly available distributed systems on AWS, MySQL, Spark, and Kubernetes.
• Experience scaling infrastructure for major sales events (e.g., Prime Day, Black Friday).
• Hands‑on expertise tuning autoscaling, CPU/Memory, and multithreaded workloads.
• Ability to deliver major features or deprecate components through clear technical plans.
• Comfort operating in ambiguous environments and navigating from low‑level code to large‑scale architecture.

Required skills

• Python
• Kotlin
• AWS
• MySQL
• Spark
• Kubernetes
• ElasticCache
• DynamoDB
• AuroraDB

What we offer

• Opportunity to influence the technical direction of a fast‑growing fintech.
• Collaborative environment with cross‑functional teams.
• Competitive compensation and benefits.