Senior Software Engineer, Backend (AI Platform)

Location: Remote in Canada, limited to candidates residing in Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, or Saskatchewan

Base pay: CAD 153,000–213,000 per year

Company

Affirm provides transparent, predictable pay-over-time products and builds global infrastructure shared across financial products, merchants, and vendors.

What you will do

• Own technical decisions and projects across design, launch, and on-call operations for the AI Platform team.
• Design and build gateways, agent runtimes, and evaluation services that move AI workloads from pilot to production.
• Build identity, quota, routing, caching, failover, cost attribution, and governance controls for models and tools.
• Partner with security, infrastructure, and product engineering teams on guardrails and on-behalf-of identity for tool access.
• Define metrics and operate production systems through monitoring, alerting, runbooks, and on-call.
• Improve engineering standards, mentor engineers, and promote effective design, coding, and testing practices.

Requirements

• 4+ years of experience designing, developing, and launching backend systems at scale using languages such as Python or Kotlin.
• Experience developing highly available distributed systems with technologies such as AWS, MySQL, and Kubernetes.
• Production experience with LLMs, agents, or AI frameworks, including inference APIs, LLM gateways, MCP, tool calling, evaluations, or agent runtimes.
• Understanding of AI usage and the infrastructure required to support AI workloads across disciplines.
• Experience defining technical plans for significant features or system components with elegant, simple, and extensible designs.
• Ability to write high-quality, understandable code and make significant changes safely in large codebases.
• Proactive approach to professional growth and feedback.
• Strong verbal and written communication skills for collaboration with a global engineering team.
• Equivalent practical experience or a bachelor’s degree in a related field.

Culture & Benefits

• Remote-first work with flexibility within the country of employment; occasional office work may be required, and new hires attend in-person onboarding.
• Blameless postmortems, detailed technical specifications, feedback gathering, and strong engineering standards.
• 100% subsidized medical, dental, and vision coverage for employees and dependents.
• Monthly technology, health, and wellness spending stipends.
• Flexible time off, generous holiday calendars, and an employee stock purchase plan.
• Inclusive interview process with accommodations available for candidates with disabilities.