Senior Software Engineer, Back-end (Fraud)

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 buyers, 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. What You'll Do You will be responsible for owning and delivering quarterly goals for your team, leading engineers through ambiguity to solve open-ended problems, and ensuring that everyone is supported throughout delivery. You will design and implement backend services and APIs using Python or Kotlin, operating within Affirm’s microservice and event-driven architecture. You will take an active role in shaping the team’s roadmap, collaborating on technical design, and driving execution across projects that span multiple teams. You will partner with the Engineering Manager and your teammates to elevate quality standards, evolve engineering processes, and represent the team in cross-functional initiatives. You will collaborate cross-functionally with stakeholders in Fraud Ops, Compliance, Product, Machine Learning, and Analytics to build scalable fraud tooling and infrastructure. You will proactively identify opportunities to improve system reliability, team efficiency, or architecture—and lead efforts to address them. You will contribute to operational excellence by maintaining high observability standards, responding to incidents, and participating in the on-call rotation. You will foster a culture of ownership, inclusion, and craftsmanship by mentoring teammates, providing feedback, and upholding high code and design standards. On-Call Rotation - There would be an on-call rotation for this role as a requirement. What We Look For 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. 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. Experience with Snowflake, dbt, Airflow, or Chronosphere (nice to have) Background in fraud prevention, risk systems, or post-transaction tooling. (nice to have) Experience working in the fintech sector or other highly regulated environments, with a strong understanding of risk, compliance, and operational constraints. (nice to have) Compensation & Benefits Base Pay Grade - N Equity Grade - 4 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 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 Affirm Holdings, Inc. (parent company). ESP base pay range per year: €85,000  -  €115,000     Additional benefits include: Flexible Spending Wallets for tech, food and lifestyle Away Days - wellness days to take off work and recharge Learning & Development programs Parental benefits Employee Resource & Community Groups We are able to offer visa sponsorship for this role, but do require that someone is based in Spain for the role. Location - Remote Spain #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.