AI Engineer Backend (Remote - ES/UK only)
Quadrivia
| Company | Quadrivia |
| Category | Engineering |
| Location | Barcelona, Spain |
| Remote | Remote |
| Employment | Not stated |
| Level | Not stated |
| Salary | Not stated by the employer |
| Posted | 6 Nov 2025 |
| Last verified | 10 Aug 2026 |
| Source | The employer's own careers page (company_site) |
Description
About Us
Quadrivia is the health technology company behind Q, a comprehensive, controllable, and customizable assistant AI built by clinicians, for clinicians. Addressing the urgent shortage of healthcare professionals, Q provides real-time, personal, and reliable support for clinical tasks across the care continuum. Designed for providers, payers, and pharmaceutical companies, Q is easy to customize and integrates seamlessly into workflows, delivering precise assistance across the care spectrum.
The Role
You'll build and run Cortex , the core AI architecture behind Qu, and the services that sit on top of it: automated AI audits, patient simulators, retrieval (RAG), and the escalation agents that take over in red-guardrail situations. This is a backend role first. The job is to make our AI systems reliable, fast, and observable in production, not to invent new ML. You own the software underneath the agents.
We're a small team that ships real systems. We've built our entire AI-driven evaluation system, our voice orchestrator, and a multi-hierarchical RAG platform from scratch.
What You'll Do
• Design and maintain robust, modular backend systems using clean architectural (SOLID) principles to ensure long-term maintainability, scalability and flexibility as the agentic stack evolves.
• Own Cortex end-to-end: architecture, API design, service boundaries, reliability targets, and proactively managing failure modes.
• Build the platform services around it. The automated audit and eval pipeline, patient simulators for testing agents at scale, and the retrieval layer.
• Write fast, well-tested Python services with FastAPI, asyncio, and pydantic, and get the queues, caching, and data stores right.
• Wire up the multi-agent orchestration: routing between agents, shared state, and clean tool interfaces.
• Engineer the RAG pipeline for high-signal retrieval (chunking, hybrid search, re-ranking, caching) and prove the grounding holds.
• Make the whole thing observable: structured logs, OTEL tracing across the agent graph, cost, latency and token visibility, dashboards, and CI gates that catch regressions before they ship.
Minimum Qualifications
• Your core is backend and software engineering. You write clean, maintainable services and you care how they behave in production.
• Deep understanding of architectural design patterns (e.g., Clean/Hexagonal Architecture, Domain-Driven Design, SOLID, event-driven) to manage complex system boundaries.
• At least 2 years, demonstrable, building or scaling user-facing AI software that real users touched. We'll want to see it.
• Expert Python, with strong FastAPI, asyncio, pydantic, and production observability.
• Comfortable with agent patterns and eval-driven development.
• You've worked at a startup before and know what wearing several hats actually costs.
Nice to Have
• Real-time and voice: WebRTC, LiveKit, SIP, VAD, barge-in, turn-taking. Useful here, not required.
• Programmatic prompt optimization techniques.
• LLM-as-judge setups and other evaluation tooling.
• GCP: Cloud Run or GKE, Pub/Sub, Vertex AI, GCS, Secret Manager, Cloud Logging and Trace.
• Healthcare data familiarity.
Example Problems You'll Tackle
• Stand up the AI audit pipeline so evals run automatically on slices of production traffic, with regression gates wired into CI.
• Build a patient simulator that lets us stress-test agents at scale before they ever reach a real call.
• Improve the RAG pipeline with hybrid retrieval and re-ranking, then prove the gains with faithfulness and context metrics.
• Get OTEL-first tracing across the agent graph, with automated eval triggers on live traffic.
• Turn EHR integrations into reliable tools the agents can call.
Tech Stack
Python, FastAPI, pydantic, asyncio, Redis, Postgres, vector stores, Docker, Kubernetes, Terraform, ArgoCD, OTEL, TypeScript, React. Real-time stacks (WebRTC, LiveKit, SIP, STT/TTS) where the work touches voice.
What Success Looks Like
• Quadrivia's backend becomes a reference for reliability, safety, and performance.
• Your services run above 99.99% availability under strict regulatory constraints.
• Other engineers build new clinical workflows and agent capabilities quickly and safely.
• AI-generated code gets reviewed, corrected, and owned by you.