Affirm Software Engineer Interview

What this interview tests

• Backend system design under real constraints — Whether it's card authorization, a merchant lifecycle-orchestrator, or a reliability dashboard, you'll be asked to design a backend service and defend the tradeoffs — including how you'd prevent a transaction from processing twice.
• State machines and event-driven architecture — The Merchant & Partner Lifecycle postings specifically want you to model onboarding, suspension, and offboarding as a state machine, and to weigh synchronous RPC against event-driven async communication.
• AI-assisted development as a working habit — The Reliability Platform postings explicitly expect you to already use Cursor, Claude, or Copilot-style tools daily, and ask how you keep quality high while moving fast with them, plus how you'd add guardrails to an AI agent that recommends incident actions.
• Turning ambiguity into a phased plan — Nearly every posting asks you to break a vague business requirement or merchant-lifecycle problem into a scoped, phased engineering plan rather than solving it all at once.
• Code review and operational ownership — On-call escalations, code review feedback, and metrics/monitoring ownership show up across the Card Management and Marketplace Performance roles as concrete, specific scenarios rather than abstract questions.

Common question themes

Likely format

None of these postings state a formal interview format, so what follows is inferred from question style alone. The repeated 'design a service' and 'walk through the tradeoffs' phrasing across postings suggests a dedicated system-design round, and the recurring on-call/code-review/feedback questions point to a separate behavioral round focused on day-to-day engineering habits. Given how consistently AI-tool usage comes up, expect at least one question in most loops about your actual coding-assistant workflow, not a hypothetical.