Senior Software Engineer, Backend (Merchant & Partner Lifecycle)

Affirm provides a transparent way for people to pay over time with no hidden fees or surprises. The Merchant & Partner Lifecycle team is building a new lifecycle-orchestrator service to simplify and isolate critical systems, improve availability, modernize legacy code, and support scalable merchant growth. This senior backend role focuses on technical leadership, cross-team collaboration, mentoring, and driving long-term architectural strategy.

Responsibilities:

• 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

Requirements:

• 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
• Excellent communication skills, both written and verbal. Must be proficient in asynchronous communication–written tech specs, ADRs, project plans, etc
• Experience designing, developing, and launching backend systems (our stack: AWS, gRPC, Snowflake, Kotlin, Python, MySQL, Kubernetes). Java and Kotlin experience are especially helpful
• Prior experience with monitoring and alerting systems (sentry.io, rollbar, chronosphere, kibana)