Senior Staff Full Stack Engineer

The Role

We're scaling rapidly across Web/Frontend and Backend/AI. To keep pace, we need a hands-on technical leader who can balance deep execution with architectural foresight. You'll bridge strategy and implementation: co-creating architecture and engineering standards with the Head of Engineering, while directly leading teams to build systems that scale sustainably—without bottlenecks.

Location: Remote — Open to candidates based anywhere in the UK/EU Time Zones.

Key Responsibilities

• Own architecture & systems design . Define high-impact decisions across frontend and backend (service boundaries, data flows, ADRs, UI composition, BFF patterns). Evolve our API and event-driven designs for scale and reliability.
• Lead execution end-to-end . Drive projects from discovery → design → implementation → production. Align scope with Product & Design, surface trade-offs early, and keep teams unblocked.
• Build excellent services . Ship robust Python/FastAPI microservices and TypeScript/React frontends (ideally Next.js ). Use Node.js (Express/Fastify/NestJS) for BFFs/edge services where it fits. Back with PostgreSQL/Redis/Elasticsearch (or OpenSearch ) for performance, resilience, and cost efficiency.
• Asynchronous comms at scale . Design and implement async workflows (Kafka/SNS/SQS/EventBridge), sagas/outbox, idempotency, retries, and back-pressure; champion distributed tracing and well-defined contracts.
• Infrastructure as code . Stand up and evolve AWS with Pulumi/Terraform (VPC, ECS/EKS or Lambda, API Gateway/ALB, CloudFront), manage secrets and networking, and automate CI/CD (GitHub Actions/ArgoCD). Use CDNs/edge where appropriate (e.g., CloudFront/Cloudflare/Vercel).
• Observability & Reliability . Establish SLIs/SLOs. Integrate logs/metrics/traces (OpenTelemetry, Prometheus/Grafana/Datadog/Sentry). Add frontend observability (RUM, error tracking, Core Web Vitals), and drive actionable alerts and incident reviews.
• Security & Governance . Apply AWS Well-Architected, least-privilege IAM, secret management, SDLC controls, and OWASP-aware web security (CSP, CSRF, SSRF mitigations). Partner on data/privacy (e.g., GDPR).
• Mentor & Uplift . Lead through design walkthroughs, pairing, and code reviews across frontend and backend. Help engineers level up and take on bigger problems.
• Greenfield & Modernisation . Lay foundations for new domains (mobile backend, new verticals) while improving existing systems (performance, reliability, cost). Guide migrations (e.g., to RSC/Next.js App Router, typed APIs).
• Team Leadership . Set engineering standards, facilitate technical planning, coordinate across squads, and influence hiring/interviews. Provide calm, decisive technical leadership.
• Cross-functionally . Turn business goals into pragmatic technical plans; communicate trade-offs clearly to non-engineers.

Qualifications

• Deep Backend Mastery : Python 3.x, FastAPI/Flask; SQL schema design & query performance; caching strategies; robust testing (pytest, property-based, integration).
• Frontend Capability : Strong TypeScript/React (Next.js preferred), component architecture, state/data fetching (TanStack Query), forms, accessibility (WCAG 2.1), performance (Lighthouse, Web Vitals), and SSR/SSG/ISR.
• Node.js experience : Building BFFs/edge APIs with Express/Fastify/NestJS; API design (REST/JSON; bonus for GraphQL/gRPC); familiarity with tRPC a plus.
• Modern Microservices : Event-driven patterns, resilience (circuit breakers, bulkheads, timeouts), contract testing, and API versioning.
• Cloud & IaC : Strong AWS (networking, compute, storage, security). Production Pulumi and/or Terraform. Containers (Docker) and orchestration (ECS/EKS) or serverless where it fits.
• Data & Search : PostgreSQL at scale; working knowledge of Elasticsearch/OpenSearch (indexing, relevance, aggregations).
• Observability Culture : You've stood up tracing/metrics/logging from scratch and used them to drive reliability—both backend and frontend.
• Leadership through Craft : Excellent taste in code, clear docs/ADRs, and steady decision-making. Proven mentorship and leading multi-team initiatives.
• Bias for Delivery : You break down complexity, make smart trade-offs, and ship.

Nice to Have (Not Required):

• Design systems (Storybook), Tailwind/Chakra, advanced forms (React Hook Form/Zod).
• GraphQL (schema design, federation), tRPC, Prisma/SQLAlchemy.
• Vector search/retrieval, ML-adjacent pipelines, feature flags/experimentation.
• WebSockets/WebRTC , background jobs/cron orchestration.
• Performance profiling (backend & frontend), cost-aware architecture.
• Experience with LangChain/agents—useful, but optional .

Why Join Healf

• Do your life’s best work: Build something that matters, with a team that moves fast and aims high
• Surround yourself with A+ talent: You’ll work with high-performers who care deeply and raise the standard every day
• Be a builder: This isn’t a cog-in-the-machine role. You’ll help shape our voice, culture, and growth
• Wellbeing is the lifestyle: From office yoga to Healf Zone insights, everything we do is rooted in our pillars: EAT MOVE MIND SLEEP
• Premium Wellhub Membership: Unlimited entry to 1000's of gym, yoga, & fitness studios (UK Only)
• Exclusive Healf Perks: 50% off all Healf products plus discounted Healf Zone blood testing.
• Nest Pension: Secure your future with our pension contributions. (UK Only)
• Wellbeing-Focused Workspace: Incredible Hammersmith office with great natural lighting (Optional Workspace if UK-Based)
• Team Connection: Annual company-wide retreat to recharge and bond.

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