Senior Software Engineer, Backend (Merchant & Partner Lifecycle)

About the Role

Affirm is reinventing credit to make it more honest and friendly. The Merchant & Partner Lifecycle (M&PL) team is leading an architectural transformation to consolidate merchant lifecycle orchestration into a cohesive domain. As Senior Software Engineer, Backend, you'll act as a technical leader designing and building the lifecycle-orchestrator service—a critical backbone connecting multiple systems—while delivering availability improvements through system simplification and modernizing legacy code.

Responsibilities

• Design and expand the platform backbone to scale to hundreds of thousands of merchants globally
• Design work scope and align with other teams to execute cross-functional projects
• Mentor engineers on their development and growth
• Partner with Engineering Manager and Team Lead to drive the team's long-term vision
• Execute technical strategy for complex, broad requirements with forward-looking approaches that solve large, open-ended problems beyond the immediate team
• Leverage agentic development tools like Claude Code to automate development workflows
• Enhance engineering standards, tooling, and processes across the organization

Requirements

• 5+ years of backend software engineering experience
• Strong understanding of Domain-Driven Design, distributed systems, and how architectural decisions impact performance and maintainability
• Proficiency with data models, API design (HTTP and RPC), state machines, event-driven architecture, and database design
• Excellent written and verbal communication skills; demonstrated proficiency in asynchronous communication through technical specs, ADRs, and project plans
• Experience designing, developing, and launching backend systems using: AWS, gRPC, Snowflake, Kotlin, Python, MySQL, and Kubernetes (Java and Kotlin experience especially valued)
• Prior experience with monitoring and alerting systems such as Sentry, Rollbar, Chronosphere, or Kibana

Benefits

• Base pay: Pay Grade N; Equity Grade 9 (new employees typically start at the beginning of the pay range; compensation determined by location, experience, and job-related skills)
• Equity rewards
• Monthly stipends for health, wellness, and tech spending

Location: Remote, US