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 team is seeking a Senior Software Engineer to lead the development of a new lifecycle-orchestrator service, enhancing system performance and modernizing the codebase. This role involves designing platform architecture, mentoring engineers, and improving engineering standards across the organization.

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)