Senior Software Engineer, Back-end (Fraud)

Location: Remote Spain
Department: Checkout

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.

The Fraud International Team (FIT) leads the engineering effort to extend Affirm's Fraud Decisioning System into markets beyond the US - Canada, the UK, Australia, and growing rapidly. We own real-time fraud decisioning for these markets, integrate region-specific risk vendors, and are building the platform that lets Affirm stand up fraud protection in a new country quickly and safely. As Affirm expands globally, FIT scales with it.

What You'll Do

• You will 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.
• You will 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.
• You will 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.