Senior Software Engineer, Backend (Cost Engineering)

Affirm, Inc.; Calgary; Remote; CAD 153,000 - 213,000; Full time

Benefits offered by this job

Health coverage at no cost

Monthly tech stipends

Equity rewards (ESPP)

Generous time off + holiday calendar

Job summary

Affirm, Inc. is seeking an experienced Capacity Modeling Engineer to own quarterly goals for the team and lead engineers through ambiguity while delivering capacity plans for peak sales events. You will translate demand forecasts into resource settings across regions and environments.

You will collaborate with product, design and analytics, establish reliable metrics, and drive on-call readiness, code quality, and scalable designs to support growth.

Qualifications

• 4+ years designing backend systems at scale using Python or Kotlin.
• Experience with highly available distributed systems (AWS, MySQL, Kubernetes).
• Experience supporting scale during major sales events (Prime Day, Black Friday, etc.).
• Tuned autoscaling, CPU/Memory, and multi-threading for compute workloads.
• Defined technical plans for delivering significant features with elegant design.
• Able to make large codebase changes safely with tooling and practices.
• Proactive about growth, feedback, and collaboration with stakeholders.
• Strong verbal and written communication for global collaboration.
• Bachelor’s degree or equivalent practical experience.

Responsibilities

• Own and deliver quarterly goals for the capacity modeling team and lead engineers through ambiguity.
• Collaborate with product, design and analytics to align on constraints and risks.
• Identify and drive resolution of project, process, technology or business issues.
• Maintain operations of artifacts, monitor metrics, and support on-call efforts.
• Set and improve code review and design standards across the team.
• Develop talent by providing feedback and guidance.

Skills

Python

Kotlin

AWS

MySQL

Kubernetes

Distributed systems

Code quality

Communication

Education

Bachelor's degree or equivalent experience

Job description

At Aff, 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 Aff**irm 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 Aff typically come in at the start of the pay range. Aff 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 Aff 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.

Remote

Remote-first with flexibility built in

Affirm 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 Aff 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

Our benefits reflect our commitment to care, transparency, and flexibility. Here are a few highlights:

• 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 Aff 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: Affirms considers qualified applicants with arrest and conviction records, as required by law.