Senior Full-Stack Engineer (Backend Leaning)

Fairmarkit is hiring a Senior Full-Stack Engineer to build and maintain sourcing products, including workflows and integrations with customers’ ERP and procurement systems. The role focuses on backend architecture, APIs, event-driven services, and data while contributing across the stack and using AI coding tools.

Responsibilities:

• Design and build features end to end, from the domain model and API to the screen, with product managers, designers, front-end engineers, and QA
• Own the hard parts of the back end -- data models, service boundaries, event flows, and the integrations that move purchase data between Fairmarkit and our customers' systems
• Build with AI coding agents every day, and hold what they produce to the same standard as code you wrote by hand
• Review code carefully. Catch design problems before they ship, keep types honest, and design out whole classes of bugs instead of relying on tests to catch them
• Move across product areas as the roadmap shifts, ramp up fast, and write down what you learn for the next person
• Raise the bar around you. Mentor engineers who are new to an area, and help shape how we build software with AI

Requirements:

• A track record of shipping production software across the stack, with real depth on the back end
• Strong fundamentals in system design, clear interfaces, type safety and well-chosen tests
• Professional experience in at least one statically typed language such as Java, C#, Go, Kotlin, Scala or Rust, alongside TypeScript and Python
• Daily, hands-on use of AI coding tools, and the discipline to review, correct and own what they produce
• Comfort walking into an unfamiliar domain, asking good questions and finding the real constraint quickly
• The habit of explaining your decisions in writing (design docs, clear pull request descriptions, decision records) so teammates can follow and build on them without a meeting. We're building a culture of asynchronous, written communication, and we want people who'll help lead it
• Experience with procurement, ERP or B2B commerce systems (Coupa, SAP Ariba, Oracle, NetSuite)
• Event-driven systems and data pipelines (Kafka, change data capture, Postgres at scale)
• Experience at a startup or growth-stage company where you owned outcomes, not just tickets
• Work that shows how you build: open source, a side project, or a write-up of how AI changed the way you work