Senior Software Engineer, Backend (AI Platform)

Location: Remote in Canada; candidates must reside 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 payment solutions that allow customers to pay over time without hidden fees.

What you will do

• Own technical decisions and projects across design, launch, and on-call operations for the AI Platform team.
• Design and build gateway, runtime, and evaluation services that scale AI workloads securely across millions of users and transactions.
• Implement identity, quota, routing, caching, and failover controls for attributable and governable AI spending.
• Partner with security, infrastructure, and product engineering teams on agent guardrails and on-behalf-of identity for tool access.
• Define metrics and own monitoring, alerting, runbooks, and operational health for shipped systems.
• Improve code review and design standards, mentor engineers, and promote effective use of AI tools and agentic workflows.

Requirements

• 4+ years of experience designing, developing, and launching backend systems at scale using 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 such as LiteLLM, MCP, tool calling, evaluations, or agent runtimes.
• Understanding of AI usage and infrastructure for supporting AI workloads across disciplines.
• Experience defining technical plans for significant features or system components using elegant, simple, and extensible designs.
• Ability to write high-quality, understandable code and make significant changes safely in large codebases using appropriate tools and practices.
• Evidence of proactively owning professional growth and seeking feedback from teams, managers, and stakeholders.
• 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; new hires attend an in-person onboarding experience.
• Blameless postmortems, detailed technical specifications, and feedback-driven engineering practices.
• 100% subsidized medical coverage, dental and vision coverage for employees and dependents.
• Monthly stipends for technology, health, and wellness spending.
• Flexible time off, generous holiday calendars, and an employee stock purchase plan.

Hiring process

• Inclusive interview process with accommodations available for candidates with disabilities.