Senior Software Engineer, Backend (Capacity Modeling)

Affirm, Inc.; United States; Remote; USD 108,000 - 151,000; Full time

Benefits offered by this job

Health coverage for employees and for

Job summary

Affim is seeking an experienced backend engineering leader to own quarterly goals, guide engineers through ambiguity, and ensure delivery excellence. You will collaborate with product, design and analytics while scaling services for high-traffic events and maintaining reliable capacity planning across regions.

You will drive architecture with emphasis on autoscaling, multi-threading, and maintainable code in a remote-first environment. Strong communication and ownership are essential.

Qualifications

• 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 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.
• Ability to define a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design.
• Proven ownership of growth, seeking feedback, and strong collaboration across teams.

Responsibilities

• Own and deliver quarterly goals for your team and lead engineers through ambiguity to solve open-ended problems.
• Collaborate with product management, design and analytics to align on risks and trade-offs.
• Proactively identify and solve project, process, technology or business issues.
• Support operations and availability of team artifacts with metrics and on-call efforts.
• Foster a culture of quality and ownership by setting code review and design standards.

Skills

Backend design

Distributed systems

Python/Kotlin

Autoscaling

Multi-threading

Communication

Ownership

Education

Bachelor's degree or equivalent practical experience

Tools

AWS

Kubernetes

MySQL

Job description

At Affim, we exist for the moments that matter—giving people a clear, predictable way to pay over time, with no hidden fees, no surprises, and no tradeoffs on what matters most. The Capacity Modeling team ensures Affim 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.

What You'll Do

• You will be responsible for owning and delivering quarterly goals for your team, leading engineers on your team through ambiguity to solve open-ended problems, and ensuring that everyone is supported throughout delivery.
• You will support your peers and stakeholders in the product development lifecycle by collaborating with product management, design & analytics by participating in ideation, articulating technical constraints, and partnering on decisions that properly consider risks and trade-offs.
• You will proactively identify project, process, technology or business issues, advocate for them, and lead in solving them.
• You will support the operations and availability of your team's artifacts by creating and monitoring metrics, escalating when needed, and supporting “keep the lights on” & on-call efforts.
• You will foster a culture of quality and ownership on your team by setting or improving 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 4+ years of experience designing, developing and launching backend systems at scale using languages like Python or Kotlin.
• You have a track record of developing highly available distributed systems using technologies like AWS, MySQL 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 defining a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design. You write high quality code that is easily understood and used by others.
• You are proficient at making significant changes in a large code base, and have developed a suite of tools and practices that enable you and your team to do so safely.
• Your experience demonstrates that you take ownership of your growth, proactively seeking feedback from your team, your manager, and your stakeholders.
• 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.

Pay Grade - N Equity Grade - 6 Employees new to Affim typically come in at the start of the pay range. Affim 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 monthly stipends for health, wellness and tech spending, and benefits (including 100% subsidized medical coverage, dental and vision for you and your dependents). In addition, the employees may be eligible for equity rewards offered by Affim Holdings, Inc. (parent company). CAN base pay range per year: CAD $153,000 - $213,000.

Location - Remote Canada

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.

This posting is for an existing vacancy.

#LI Remote Remote-first with flexibility built in

Affim is proud to be a remote-first company. Most roles can be done from almost anywhere within the country of employment. Some positions may occasionally require in-person work at an Affim office, and a few are office-based due to the nature of the work. All new hires will be invited to attend an in-person onboarding experience.

Benefits designed for you

• Health coverage at no cost: We cover 100% of premiums for employees and their dependents.
• Spending stipends: Monthly stipends support your tech setup, and the ability to choose health and wellness options that are right for you.
• Time off to recharge: Flexible time off and generous holiday calendars help you rest when you need to.
• Own a piece of what you build: Our employee stock purchase plan (ESPP) lets you buy Affim stock at a discount.

We’re committed to providing an inclusive interview process, including accommodations for candidates with disabilities. If you need support, we’re happy to help.

For positions based in San Francisco or Los Angeles: Affim considers qualified applicants with arrest and conviction records, as required by law.