Staff Software Engineer, Backend (Capacity Modeling)

Affirm; St. Louis (MO); On-site; USD 200,000 - 250,000; Full time

Benefits offered by this job

Health care coverage

Flexible Spending Wallets

Competitive vacation and holiday schedules

Employee stock purchase plan (ESPP)

Job summary

Affirm is seeking a seasoned backend systems developer in St. Louis to lead technical strategy and collaborate across teams for project execution. Ideal candidates should have over 8 years of experience in developing distributed systems with expertise in languages like Python or Kotlin. A strong grasp of AWS, MySQL, and Kubernetes is essential, along with a degree in a related field or equivalent experience. Affirm offers a remote-first work environment with competitive health benefits and a transparent pay structure, ranging between $200,000 to $250,000, based on location and experience.

Qualifications

• 8+ years of experience designing, developing and launching backend systems at scale.
• Experience with highly available distributed systems.
• Experience supporting large scale sales events.

Responsibilities

• Set technical strategy for the team on a year-long basis.
• Collaborate across teams throughout the product development lifecycle.
• Ensure operational processes and monitoring are in place.

Skills

Backend systems design and development

Python or Kotlin

AWS

MySQL

Spark

Kubernetes

Education

Bachelor's degree in a related field or equivalent experience

Job description

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 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 then convert those forecasts into recommended capacity settings such as pod counts, HPA ranges, and/or infrastructure sizing changes across regions and environments. The coverage of infrastructure resources includes not only Compute but also infrastructure such as ElasticCache, DynamoDB, AuroraDB, and more.

What You'll Do

• 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, policies, 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, Spark and Kubernetes.
• You have experience supporting scale up and down of large scale sales event such as Prime Day, Black Friday Cyber Monday, or other sales holidays.
• You have tuned autoscaling, CPU/Memory, and multi-threading for compute type workloads.
• 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 impact trajectory demonstrates that you have mastered gathering and iterating on feedback from your engineering and cross-functional peers.
• You have strong verbal and written communication skills that support effective collaboration with our global engineering team.
• This position requires either equivalent practical experience or a Bachelor’s degree in a related field.

Base Pay Grade - P

Equity Grade - 13

Employees new to affirm typically come in at the start of the pay range. affirm focuses on providing a simple and transparent pay structure which is based on a variety of factors, including location, experience and job-related skills. 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: $225,000 - $275,000

USA base pay range (all other U.S. states) per year: $200,000 - $250,000

Affirm is proud to be a remote‑first company! The majority of our roles are remote and you can work almost anywhere within the country of employment. affirmers in proximal roles have the flexibility to work remotely, but will occasionally be required to work out of their assigned affirm office. A limited number of roles remain office-based due to the nature of their job responsibilities.

Benefits

• Health care coverage - affirm covers all premiums for all levels of coverage for you and your dependents
• Flexible Spending Wallets - generous stipends for spending on Technology, Food, various Lifestyle needs, and family forming expenses
• Time off - competitive vacation and holiday schedules allowing you to take time off to rest and recharge
• ESPP - An employee stock purchase plan enabling you to buy shares of affirm at a discount

We believe It’s On Us to provide an inclusive interview experience for all, including people with disabilities. We are happy to provide reasonable accommodations to candidates in need of individualized support during the hiring process.

For U.S. positions that could be performed in Los Angeles or San Francisco Pursuant to the San Francisco Fair Chance Ordinance and Los Angeles Fair Chance Initiative for Hiring Ordinance, affirm will consider for employment qualified applicants with arrest and conviction records.

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