Senior Software Engineer, Back-end (Fraud)

About the Position

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 Fraud Engineering organization builds the foundational and tactical software that enables Affirm to respond strategically to fraud - both in real time and after the transaction. Our mission is to support business growth while protecting Affirm, our customers, and our merchants. We evaluate risk at critical decision points in the user journey, rapidly adapt to evolving fraud patterns, and equip operations teams with the tools needed to investigate and mitigate fraud at scale.

We’re looking for a Senior Software Engineer to join our fully remote team based in Europe. You’ll collaborate closely with stakeholders across North America - including teams in Product, Compliance, Machine Learning, Fraud Operations, Fraud Strategy, and other Fraud Engineering teams.

Responsibilities

• Own and deliver quarterly goals for your team, leading engineers through ambiguity to solve open-ended problems, and ensuring that everyone is supported throughout delivery.
• Design and implement real-time fraud decisioning services and APIs in Python or Kotlin, extending Affirm's Fraud Decisioning System to markets beyond the US.
• Build and evolve the platform and tooling that let Affirm launch fraud decisioning in a new country quickly-turning market-by-market setup (rules, models, and vendor configuration) into a repeatable, low-friction path so launches scale sub-linearly with the number of markets.
• Integrate region-specific fraud and risk vendors and help operationalize the machine learning and AI signals that power real-time decisioning, while using modern AI tooling to move faster as an engineer.
• Support peers and stakeholders across the product development lifecycle - collaborating with Product, Machine Learning, Analytics, and Fraud Strategy, articulating technical constraints, and partnering on decisions that properly weigh risks and trade-offs.
• Support the operations and availability of your team's systems by creating and monitoring metrics, escalating when needed, and contributing to keep-the-lights-on and on-call efforts.
• Foster a culture of quality and ownership - setting and improving code review and design standards, mentoring teammates, and leading by example.

Requirements

• 5+ years of experience building backend systems at scale using Python or Kotlin.
• Experience with distributed systems and infrastructure using AWS, MySQL/PostgreSQL, and Kubernetes.
• Strong system design skills and a track record of delivering maintainable, extensible services.
• Fluency with AI-driven engineering - every Affirm engineer builds with tools like Claude Code and most PRs are co-authored with AI, so directing and orchestrating AI and excelling in the reviewer's seat (setting intent, critically evaluating generated code, and owning its correctness, quality, and security) is a core expectation.
• Proficiency in SQL and working with data-rich environments.
• Familiarity with CI/CD practices and safe production deployments.
• Strong written and verbal communication skills, especially in distributed teams.
• A proactive, ownership-driven mindset with a focus on learning and team success.

Nice to Have

• Experience with Snowflake, dbt, Airflow, or Chronosphere.
• Background in fraud prevention, risk systems, or real-time decisioning.
• Experience building for multiple markets or regions - internationalization or localization.
• Experience working in the fintech sector or other highly regulated environments, with a strong understanding of risk, compliance, and operational constraints.

We Offer

• Base Pay Grade N: 308,000 zł - 428,000 zł per year.
• Equity: New hire equity: $32,000-$48,000 and Annual Refresh: $10,000.
• Reward equity: $0-$150,000.
• Flexible Spending Wallets: Up to 1390 zł per month.
• Comprehensive Benefits:
  • Competitive paid time off, paid public holidays, and additional paid Away Days.
  • Comprehensive private healthcare through Lux Med's Platinum package.
  • A MultiSport card to support your health and well-being.
  • Learning and development programs.
  • Family healthcare support through Maven and parental leave support through Parentaly.
  • Mental well-being support through Lyra, including up to 12 confidential counseling or coaching sessions each year for you and your household members.
  • Financial well-being support through Northstar, with unlimited access to Certified Financial Advisors and planning tools at no cost to you.
  • Employee Resource Groups (ERGs) that foster connection and inclusion.
  • Eligibility for creative tax benefits, subject to applicable law, role, and company policy.

About the Company

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.

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