Senior Software Engineer, Backend (Comms Core)

At Affirm, we exist for the moments that matter, giving people a clear, predictable way to pay over time. The Engineering team builds systems that power Affirm's mission, focusing on reliable, performant, and scalable solutions. Affirm's Communications team builds and modernizes the highly available platform that delivers billions of customer messages reliably and on time across the customer journey. As a senior backend engineer, you will shape multi-region, multi-tenant infrastructure, APIs, and vendor integrations that help product teams communicate with customers at scale. Location: Remote Spain. Must be based in Spain for the role.

Responsibilities

Own and deliver quarterly technical goals for the Communications area, collaborating with teammates to solve ambiguous, open-ended problems across messaging infrastructure; Design and evolve reliable backend services for high-volume communications across multi-region, multi-tenant environments, including orchestration, delivery, preferences, templates, and observability; Collaborate with product management, design, analytics, security, and engineering partners throughout the product lifecycle, articulating technical constraints and balancing customer impact, risks, and trade-offs; Design, implement, and operate resilient integrations with external messaging vendors, balancing reliability, latency, cost, and compliance; Proactively identify and solve project, process, technology, or business issues that affect scalability, developer experience, and operational resilience; Support the operations and availability of team services by defining service-level objectives and metrics, improving alerting and incident response, and participating in on-call efforts; Foster quality and ownership by improving design, testing, code review, rollout, and operational standards, and advocating for them through writing and tech talks; Help develop talent on the team by providing feedback, mentorship, and technical direction, and leading by example; On-call rotation is a requirement for this role

Requirements

5+ years of experience in software development or engineering, with a deep understanding of system design and architecture; Proficiency in modern programming languages such as Python, Kotlin, or similar; Track record of developing highly available distributed systems using technologies like AWS, MySQL, DynamoDB, and Kubernetes; Experience designing multi-region, multi-tenant platforms with strong isolation, scalability, failure recovery, and data-consistency guarantees; Experience integrating with third-party communications or messaging vendors and designing abstractions that account for different capabilities, rate limits, and failure modes; Experience defining a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design, and writing high quality code that is easily understood and used by others; Proficiency at making significant changes in a large code base, with a suite of tools and practices that enable safe changes; Proficiency with AI-assisted development tools and sound judgment in validating their outputs; Takes ownership of growth, proactively seeking feedback from team, manager, and stakeholders; Strong verbal and written communication skills that support effective collaboration with a global engineering team

Benefits

100% subsidized medical coverage, dental and vision for employees and dependents; Monthly stipends for health, wellness and tech spending; 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; Flexible time off and generous holiday calendars; Employee stock purchase plan (ESPP) at a discount; Possible equity rewards offered by Affirm Holdings, Inc.; Visa sponsorship available for this role