Healf
Principal Backend Engineer
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Principal Backend Engineer – Wellbeing Intelligence Platform
About the Role: The Systems Thinker
We’re looking for a systems engineer—someone who anticipates failure before it occurs, designs for scale at the outset, and makes irreversible decisions with deliberate care.
You might be a:
- Staff Engineer at a growth-stage company
- Principal Engineer at an established tech firm shaping infrastructure
- Veteran who built scale for platforms like Monzo (core banking), Deliveroo (dispatch system), or data pipelines that now feel ubiquitous
We're not interested in titles—only your ability to:
- Design backend systems from first principles
- Defend trade-offs under pressure
- Own outcomes when requirements change at 11pm on a Thursday
What We’re Building: The Future of Wellbeing
Healf is Europe’s fastest-growing health platform, with:
- £100M+ revenue run-rate
- 700K+ customers
- A high-retention, high-margin marketplace spanning EAT, MOVE, MIND, SLEEP—and beyond.
From marketplace to operating system: We’re transforming how the world optimises wellbeing through:
- A personalised wellbeing intelligence engine
- Longitudinal health data capture
- AI agents that solve user needs dynamically
- A closed feedback loop where decisions are algorithm-driven, not influence-driven
Our ambition: Replace guesswork with intelligence. We’re the OS for living well.
Why This Role? Buildings the Decisive Foundations
This is a true greenfield project. Zero legacy code to inherit. As the Founding Backend Engineer, you are the architect defining:
- The data model, pipeline architecture, and infrastructure bets that compound over time
- Right choices = years saved
- Wrong choices = years of rework
We don’t create busywork roles here. This is for engineers who’ve already built systems at pivotal points—and0 this moment exists right now, waiting for someone to see it.
What You Will Own ( Madeira Stuff)
✔ Core Backend Architecture
Design from first principles:
- API layer
- Data pipelines
- Async processing
- Infrastructure stack choices
Reasons to use Rodeo
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It searches the market for you
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No noise. No "maybe this fits." Just roles with a clear explanation of why they're right — and where to focus when applying.
Why it matters: The decisions you make in the next 12 months will shape outcomes in Year 3+.
✔ Integration Layer (Backend ↔ AI)
Own how the backend connects to the AI/ML systems the AI Engineer is building:
- Real-time personalisation
- User behaviour pipelines
- Health data inputs
Define the seam—this is your design space.
✔ Build vs Buy Decisions
Authority with the nuance and context to make the right trade-offs. When do you:
- Build?
- Buy?
- Defer?
Not slingshot execution—real system-level calls.
✔ Observability Layer
Not an afterthought, but the foundation of production reliability:
- Monitoring
- Alerting
- Instrumentation
- Detect issues before users notice them.
✔ Engineering Principles
Not a style guide. A codex that governs quality, velocity, and long-term consequences for this team.
What You’ll Deliver in the First 12 Months
- A production-grade backend powering personalised decisioning for hundreds of thousands of users
- A scalable data architecture designed for international growth
- A headerless API and pipeline layer for the AI Engineer to build on without constraints
- Full observability across every critical system from day 1
- Infrastructure decisions compounding in the right direction
Requirements
Must-Have (Core Signal)
- System design expertise is the single most important bar. We care less about your CV than your ability to:
- Analyse an unfamiliar system
- Break it down into the right blocks
- Offer the right trade-offs
- Adapt dynamically as requirements change
- Extreme ownership is non-negotiable:
- If something is missing, build it.
- If something is broken, fix it.
- No blockers left unattended. Never.
- Own outcomes, not just outputs.
Technical Fluency
- Production-grade backend architecture with:
- Experience building at scale in Python (primary), with Go for performance-critical services
- REST and event-driven API design
- Microservices trade-offs (not ivory-tower theory)
- Real-time data pipelines and async processing:
- Kafka, Celery, or alternatives
- Production experience only
- Infrastructure and DevOps fluency:
-/docker and Kubernetes
- AWS/GCP architecture decisions (not just operations)
- CI/CD design, not execution-only
- Persistence:
- Database design across relational & non-relational stores
- Service-layer data modelling at scale
- AI/ML integration:
- Bonus: Experience embedding LLMs into production backends
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How You Work
- AI collaboration
- Native tools like Claude, Cursor, Copilot in your flow
- Know how they speed payloads and where they risk harm
- Operate with imperfection
- Make informed decisions despite incomplete information
- Own consequences no matter what
- Work from vision, not specs
- Thrive when ambiguity isn’t just acceptable—it’s necessary
- Build fast, but last too
- Speed and quality are both hardware
We’re Not Looking For…
Anti-What We Want
- Engineers constrained by "narrow, well-defined scopes"—when ambiguity arrives, everyone should shine
- Wait-and-see task takers
- biri’s biggest red flag? **Passivity. **You need proactive, visionary builders
- People-managers rafted into this by ladder-climbing credentials
- Leadership requires depth OR you’ll under-serve this role
- Follow-the-checklist engineers
- We move through hypotheses, not fixed project specs
What We’re Offering
We ask for genuine commitment, but in return, give:
- Competitive base
- Meaningful equity
- Day 1 access to the co-founder
- The engines to build properly
- A team shaped by the work itself
- Creative freedom—This is career-defining backend work.
This is Europe’s fastest-growing health platform with a small-team big-impact culture. If you want to build this kind of system in your career, this is where it starts.
“It took my CV and asked me questions relevant to understanding what kind of jobs to suggest for me. Suggestions were almost perfect. Jobs were exactly what I’ve been looking for.”
Jessica, London
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