Senior Software Engineer, Backend (Consumer Data Platform)

At Affirm, 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 Growth Platform Engineering team builds the core systems and tools that drive user acquisition, engagement, and lifecycle growth at Affirm. Our platform enables personalized communications, intelligent experimentation, and scalable services that help customers discover and adopt Affirm’s products. We collaborate closely with Product, Data Science, and Experience teams to design APIs, event-driven services, and experimentation frameworks that reach millions of customers across thousands of merchants. This team’s work directly impacts how customers experience Affirm and fuels our long-term growth. We’re looking for a passionate Senior Software Engineer to design and build backend systems that power Affirm’s growth engine. This is a high-impact, cross-functional role that combines technical excellence with strong product intuition. You’ll contribute to scalable, secure, and extensible services that enable Affirm to reach new customers, improve engagement, and expand our product ecosystem. The systems you build will directly influence customer experiences and Affirm’s overall growth trajectory. What you'll do Drive planning and prioritization of projects based on product, technical, and business goals using data-driven decision making. Design and build scalable backend systems, APIs, and data models that power communications, experimentation, and personalization. Partner with Product Managers, Data Scientists, and Analysts to define and execute strategies for customer acquisition and engagement. Establish and uphold engineering best practices to ensure services are secure, observable, and performant at scale. Mentor and support junior engineers, contributing to a culture of learning, collaboration, and technical excellence. What we look for 6+ years of experience as a Software Engineer with a focus on backend systems. Strong understanding of distributed systems, service-oriented architecture, and how architectural choices affect scalability, reliability, and maintainability. Proven track record of delivering complex backend systems in production environments. Excellent written and verbal communication skills, with proficiency in asynchronous communication (design docs, technical specs, project plans, etc.). Demonstrated ability to collaborate effectively across Product, Data Science, Analytics, and Design teams. Proficiency in Python, Kotlin, or similar languages (experience with both is a plus). Experience with AWS or other major cloud providers. Bachelor’s degree in a related field or equivalent practical experience. Experience with experimentation platforms (A/B testing frameworks, feature flagging systems). Familiarity with event-driven architectures and stream processing tools (e.g., Kafka, Kinesis). Exposure to…