Senior Software Engineer, Backend (Capacity Modeling)

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/or infrastructure sizing changes across regions and environments. This remote role is open only to candidates residing in Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, or Saskatchewan.

Responsibilities

Own and deliver quarterly goals for the team, leading engineers through ambiguity to solve open-ended problems and ensuring everyone is supported throughout delivery; Support peers and stakeholders across the product development lifecycle by collaborating with product management, design and analytics, articulating technical constraints, and partnering on decisions that consider risks and trade-offs; Proactively identify project, process, technology or business issues, advocate for them, and lead in solving them; Support the operations and availability of team artifacts by creating and monitoring metrics, escalating when needed, and supporting keep-the-lights-on and on-call efforts; Foster a culture of quality and ownership by setting or improving code review and design standards, and advocating for them beyond the team; Help develop talent on the team by providing feedback and guidance and leading by example

Requirements

4+ years of experience designing, developing and launching backend systems at scale using languages like Python or Kotlin; Track record of developing highly available distributed systems using technologies like AWS, MySQL 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 defining a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design, and writing high quality code that is easily understood and used by others; Proficiency at making significant changes in a large code base, with a suite of tools and practices to do so safely; Takes ownership of growth, proactively seeking feedback from team, manager, and stakeholders; Strong verbal and written communication skills to collaborate with a global engineering team

Benefits

100% subsidized medical coverage, dental and vision for employee and dependents; Monthly stipends for health, wellness and tech spending; Possible equity rewards offered by Affirm Holdings, Inc.; Flexible time off and generous holiday calendars; Employee stock purchase plan (ESPP) to buy Affirm stock at a discount