Affirm
Senior Software Engineer, Backend (AI Platform)
$173K–$255K
Remote US +1 · Remote · Senior · Full-time · Posted Oct 26, 2026
- Location
- Remote US
Remote Canada - Experience
- 4+ years designing, developing, and launching backend systems at scale.
- Education
- Bachelor’s degree in a related field or equivalent practical experience.
About the job
Build and operate Affirm’s AI platform services—including gateways, runtimes, and evaluation systems—to bring secure, governed AI workloads into production at scale.
What you'll do
- Own technical decisions and projects from design through launch and on-call; build AI gateway, runtime, and evaluation services.
- Develop controls for identity, quotas, routing, caching, failover, cost attribution, and governed tool access; partner with security, infrastructure, and product teams.
- Monitor operational health and metrics, improve engineering standards, and mentor engineers.
What they ask for
- 4+ years designing, developing, and launching large-scale backend systems using languages such as Python or Kotlin.
- Track record building highly available distributed systems using technologies such as AWS, MySQL, and Kubernetes.
- Practical production experience with LLMs, agents, or AI frameworks, such as inference APIs, gateways, MCP, tool calling, evaluations, or agent runtimes.
- Experience planning and delivering significant system components, working safely in large codebases, and communicating effectively.
Pay
$195,000 - $255,000 USD base salary (USA: CA, WA, NY, NJ, CT); $173,000-233,000 USD base salary (USA: all other U.S. states)
Tools
Python, Kotlin, AWS, MySQL, Kubernetes, LiteLLM, Claude, ChatGPT
AI focus
Build and operate AI gateways, agent runtimes, evaluation and observability services, and governance controls; productionize AI workloads and use AI tools and agentic workflows in daily engineering work.
Model-written summary · the original posting is authoritative