Software Engineer, Backend; Capacity Modeling

Staff Software Engineer, Backend (Capacity Modeling)

Remote US

Affirm is reinventing credit to make it more honest and friendly, giving consumers the flexibility to buy now and pay later without any hidden fees or compounding interest.

The Capacity Modeling team ensures that we can safely handle forecasted traffic—especially during peak sales events—by translating demand forecasts into concrete, testable capacity plans. We 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 then convert those forecasts into recommended capacity settings such as pod counts, HPA ranges, and infrastructure sizing changes across regions and environments.

The coverage includes not only compute but also infrastructure such as Elastic Cache, Dynamo

DB, Aurora

DB, 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 for the team through definition and advocacy of technical solutions and operational processes.
• Own the team’s operations and availability by implementing monitoring, triage rotations, playbooks, policies, testing, and alerting 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 by providing feedback, 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 building highly available distributed systems with technologies such as AWS, MySQL, Spark, and Kubernetes.
• Experience scaling systems for large sales events such as Prime Day, Black Friday, Cyber Monday, or other holidays.
• Expertise tuning autoscaling, CPU/Mem, and multi‑threading for compute workloads.
• Proven ability to deliver major features and components, deprecating existing functionality through technical and execution plans.
• Comfort in ambiguity, from low‑level language idioms to large‑scale architecture.
• Demonstrated growth and impact trajectory, gathering and iterating on feedback from peers.
• Strong verbal and written communication skills to collaborate effectively with a global engineering team.
• Either equivalent practical experience or a Bachelor’s degree in a related field.

Base pay ranges (2024):
California, Washington, New York, New Jersey, Connecticut: $225,000 – $275,000 per year
All other U.S. states: $200,000 – $250,000 per year

Benefits include equity rewards, monthly stipends for health, wellness, and tech spending, 100% subsidized medical, dental, and vision coverage for you and dependents.

• Health coverage—Affirm covers all premiums for all levels of coverage for you and your dependents.
• Flexible Spending Wallets—generous stipends for technology, food, lifestyle needs, and family forming expenses.
• Time off—competitive vacation and holiday schedules allowing you to rest and recharge.
• ESPP—An employee stock purchase plan enabling you to buy shares at a discount.

Affirm is an equal opportunity employer. We are committed to building an inclusive culture where everyone has an equal opportunity to thrive.