Staff Software Engineer, Backend (Capacity Modeling)
WFA Digital Insight
Affirm’s Capacity Modeling team sits at the intersection of data science and infrastructure, translating traffic forecasts into concrete resource plans that keep the checkout experience smooth during peak shopping days. The Staff Software Engineer will shape the technical roadmap for a year‑long horizon, guiding decisions that affect pod counts, auto‑scaling policies, and regional resource sizing. What makes this role distinct is the blend of high‑level strategy with hands‑on ownership of monitoring, alerting, and on‑call rotation—rare in many backend positions that stay purely in code. Candidates should be comfortable navigating ambiguous requirements, collaborating across product, design, and analytics, and championing quality standards that ripple beyond their own team.
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: 230,000 - 290,000
USA base pay range (all other U.S. states) per year: 204,000 - 264,000
#LI-Remote
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.
We’re extremely proud to offer competitive benefits that are anchored to our core value of people come first. Some key highlights of our benefits package include:
- 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.
By clicking "Submit Application," you acknowledge that you have read Affirm's Global Candidate Privacy Notice and hereby freely and unambiguously give informed consent to the collection, processing, use, and storage of your personal information as described therein.
How to Stand Out
- Highlight any experience you have with autoscaling, especially during high‑traffic sales events, in both your resume and interview examples.
- Prepare a short case study showing how you built or refined a capacity model, including the metrics you tracked and the business impact.
- Demonstrate proficiency in Python or Kotlin by sharing a clean, well‑documented code sample or GitHub repo relevant to backend services.
- Be ready to discuss how you handle on‑call rotations and incident response; concrete stories about past incidents are valued.
- Research Affirm’s public statements on credit transparency and incorporate that understanding into your interview answers to show cultural fit.
- When negotiating, reference the Base Pay Grade (P) and Equity Grade (13) to ensure you’re aligned with their internal compensation framework.
- Watch for vague descriptions of “remote stipend” or “flexible schedule”; ask clarifying questions during the offer stage to confirm the exact remote‑work benefits.
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