Senior Backend Engineer, AI Platform & Inference Gateway

Affirm, Inc.; Austin (TX); Remote; USD 173,000 - 255,000; Full time

Benefits offered by this job

Health coverage

Tech stipends

Flexible time off

ESPP

Job summary

Affirm, Inc. is seeking a senior backend engineer to design, build, and own scalable AI platform services. You will craft gateway, runtime, and evaluation components, ensuring secure and scalable AI workloads for millions of users while collaborating with security, infra, and product teams.

You will work on identity, quota, and routing controls, develop operator-ready systems, and mentor engineers, with a strong emphasis on maintainable design and robust code.

Qualifications

• 4+ years designing, developing, and launching backend systems at scale using Python or Kotlin.
• Proven track record of highly available distributed systems using AWS, MySQL, and Kubernetes.
• Experience building with LLMs, agents, or AI frameworks in production.
• Understanding AI usage and the infrastructure to support AI workloads.
• Ability to define a technical plan for delivering a major feature with simple, extensible design.
• Experience making significant changes in a large code base with tooling that enables safe updates.
• Demonstrated ownership of growth and willingness to seek feedback.
• Strong verbal and written communication for global collaboration.
• Equivalent practical experience or a Bachelor’s degree in a related field.

Responsibilities

• Plan, execute, and own technical decisions and projects within the AI Platform team, from design through launch and on-call.
• Design and build the gateway, runtime, and evaluation services that scale AI workloads across millions of users.
• Implement identity, quota, routing, caching, and failover controls for model adoption.
• Collaborate with security, infra, and product teams to set guardrails for tool access.
• Create and monitor metrics, and maintain operational health, including monitoring and on-call readiness.
• Set and improve code review and design standards beyond your team through writing and talks.
• Leverage AI tools and agent workflows daily to amplify your output and learning.
• Educate, mentor, and grow engineers in the team.

Skills

Python

Kotlin

Distributed systems

AWS

MySQL

Kubernetes

LLMs/AI frameworks

On-call/ops

Education

Bachelor’s degree in a related field

Tools

LiteLLM

MCP Gateway

Agent Runtime

Job description

Affirm, Inc. is seeking a senior backend engineer to design, build, and own scalable AI platform services. You will craft gateway, runtime, and evaluation components, ensuring secure and scalable AI workloads for millions of users while collaborating with security, infra, and product teams.

You will work on identity, quota, and routing controls, develop operator-ready systems, and mentor engineers, with a strong emphasis on maintainable design and robust code.