Senior Software Engineer, Backend (Merchant & Partner Lifecycle)

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 Merchant & Partner Lifecycle (M&PL) team is at the forefront of Affirm’s architectural transformation. We are addressing critical architectural risks by consolidating merchant lifecycle orchestration into a newly cohesive domain. You will act as a technical leader responsible for building out the brand new lifecycle-orchestrator service that’s at the heart of multiple connected systems. Your work will deliver immediate availability improvements through system simplification and isolation, and modernize older parts of the codebase. What You'll Do • Design & expand the backbone of our platform to scale to hundreds of thousands of merchants from all around the world • Design and align the scope of work with other teams to deliver cross-team projects • Mentor other engineers to ensure their development & growth • Partner with Engineering Manager and Team Lead to drive and execute the long-term vision of the team • Execute technical strategy for broad or complex requirements with insightful and forward-looking approaches that go beyond the direct team and solve large open-ended problems • Utilize agentic development tools like Claude Code to automate parts of the development process • Improve engineering standards, tooling, and processes throughout the organization What We Look For • 5+ years of experience as a backend software engineer • A strong understanding of Domain-Driven Design, distributed systems, and how architectural decisions affect performance and maintainability • Proficiency with data models, API design (http and RPC), state machines, event-driven architecture, and database design • Exc…