Senior Backend Engineer

Senior Backend Engineer – AI Integrations Location: Remote (SPAIN only, Madrid strong preference) Department: Engineering About Northwind Robotics Northwind Robotics is building the future of autonomous accounting using AI. We help finance teams eliminate manual invoice processing and unlock real-time financial intelligence by combining advanced machine learning, OCR, and scalable backend systems. Our platform processes hundreds of millions of invoices with exceptional accuracy, and we’re just getting started. We’re a venture-backed, product-driven company solving deeply technical problems at scale, and we’re looking for engineers who want to build real AI systems that run in production for real customers. The Role We're seeking a Senior Backend Engineer to join the team behind our AI-first, in-house iPaaS: the integration platform that connects our customers' ERP and financial systems to Northwind Robotics. It reliably syncs data into Vic and pushes results back out at scale, with AI used to accelerate how quickly we onboard new customers. You'll spend the majority of your time building and operating this platform, and you'll also contribute across our broader backend surface (Public API and core services) as priorities demand. This is a hands-on, senior-level role for an engineer who thrives in complex, high-scale environments and takes pride in building reliable, performant systems. What You’ll Do Build and operate integrations that move data bidirectionally between customers' ERP systems and Northwind Robotics. Develop backend services in TypeScript/Node.js (HTTP APIs, queue-based workers, PostgreSQL). Design integrations against third-party APIs (REST, SOAP, OData, OAuth2) with explicit, typed contracts. Make jobs idempotent and replay-safe, including retries, rate limiting, dead-lettering, and correlation/audit logging. Own services from development through production, including deployment on AWS, monitoring, and issue resolution within defined SLAs. Contribute to the AI-assisted tooling that speeds up customer onboarding. Support adjacent backend domains as needed (Public API and core services in Elixir/Phoenix, plus Python services). Contribute to architectural decisions and long-term platform scalability. Identify, troubleshoot, escalate, and resolve issues related to performance, accuracy, and system stability. Our Stack Backend: Elixir/Phoenix and TypeScript/Node.js, plus Python for our AI and ML services Frontend: React + TypeScript Data & processing: PostgreSQL with queue-based, distributed processing (RabbitMQ, Oban, BullMQ) Infrastructure: AWS, containerized deployment (Docker/Kubernetes), with first-class observability and structured logging Tooling & delivery: GitHub, GitHub Actions CI/CD What You’ll Bring Bachelor’s or Master’s degree in Computer Engineering, Computer Science, or a related field (preferred). 5+ years building and operating production backend systems, primarily in TypeScript/Node.js, Elixir/Phoenix, Python. Strong backend engineers from other stacks who are eager to work in TypeScript are welcome. Experience building on top of LLMs. Experience integrating with third-party APIs (REST, SOAP, OData, OAuth2, webhooks). Solid grasp of queue-based and distributed systems: idempotency, retries, dead-lettering, and backpressure. Proven experience taking systems from development to production and operating them using best practices. Strong understanding of performance monitoring, logging, observability, and operational reliability. Experience scaling and optimizing relational databases. Exposure to IT security principles and demonstrated adherence to secure development practices. Ability to work independently, take ownership, and operate effectively in a fast-moving environment. Why Work at Northwind Robotics Build real AI systems that operate at scale in production. Own critical backend infrastructure that directly impacts customers. Work alongside experienced engineers, data scientists, and product leaders. Tackle complex technical challenges with autonomy and accountability. Be part of a company redefining how finance teams operate, using AI that actually works. If you’re excited about building intelligent backend systems, owning production-grade AI pipelines, and pushing the boundaries of applied machine learning in real-world environments, we’d love to meet you.