Full Stack Engineer

The Role

We are looking for a Senior Full-Stack Engineer to own and drive the technical evolution of Helda across both the React frontend and the Python backend. You will be the primary engineer responsible for the platform end-to-end, from the dashboards and AI conversational interface that healthcare professionals interact with daily, to the FastAPI analytics pipeline.

This is a senior, high-ownership role. You will make architectural decisions, ship production code across the full stack, build and refine data visualisations, and ensure the platform scales reliably as we onboard more healthcare organisations. You will work closely with the data engineer (who manages data ingestion and quality) and the designer (who provides Figma specifications).

What You Will Do

Frontend — React Application

• Dashboard & Data Visualisation
• Component Library & Design System
• Maintain and extend shared components: sidebar navigation, green-themed wrappers, heading styles, consent banners, device guards
• Implement animations and transitions using Framer Motion and GSAP for page transitions, loading states, and micro-interactions
• Build responsive layouts that work across desktop monitors commonly found in hospital admin offices
• Frontend Architecture — Manage application state through React Context providers (auth, analytics data, streaming, chat history, navigation, idle timeout)
• Optimise bundle size and load performance (code splitting, lazy loading, asset caching)

Backend — Python Analytics Engine

• Analytics Engine
• Design and implement new analytics operations
• Extend the sector-based plugin system to support new healthcare verticals with sector-specific schemas and formatters
• Optimise DataFrame operations for performance as datasets grow
• API & Infrastructure - Build and maintain FastAPI endpoints with rate limiting, API key authentication, and CORS policies
• Manage the request pipeline: input validation, prompt injection detection, PII scanning (input and output), policy enforcement
• Improve the plan cache system for faster repeat-query responses
• Support deployment (frontend) and secure remote access tunnels (backend)

Cross-Cutting

• Quality & Safety - Write comprehensive tests across both stacks: Jest and React Testing Library for the frontend, pytest for the backend
• Maintain type safety with TypeScript strict mode on the frontend
• Maintain the safety layer: page-scope enforcement, governed topic detection, emergency request handling, PII scanning on both inputs and outputs

Architecture & Technical Leadership

• Make and document architectural decisions across the full stack
• Review code from other contributors with an eye for correctness, performance, and security
• Identify and address technical debt that affects product quality
• Drive improvements to the AI conversational experience based on user feedback data (thumbs up/down patterns)

Required Skills

Must Have

• 5+ years professional software engineering with production experience in both frontend and backend
• Strong React proficiency (hooks, context, functional components) with TypeScript
• Strong Python proficiency - pandas, NumPy, async programming, FastAPI or similar
• Experience building data-heavy dashboards with charting libraries (Recharts, D3, Chart.js, or similar)
• Solid CSS skills - Tailwind CSS, responsive design, CSS Grid/Flexbox, and the ability to translate Figma specs to pixel-perfect UI
• Experience building REST APIs, with input validation, and input validation
• Experience with streaming/real-time UI — SSE, WebSocket, or fetch-based streaming with progressive rendering
• Strong debugging skills — ability to trace an issue from the UI through the API layer, classifier, LLM router, executor, and formatter
• Comfortable with Git workflows, code review, and test-driven development
• Demonstrated ability to make architectural decisions and own their outcomes