Senior Frontend Engineer - Growth Experimentation

black.ai; Greater London; On-site; GBP 70,000 - 90,000; Full time

Job summary

Eucalyptus in Greater London is looking for a Senior Frontend Web Engineer to take ownership of its frontend platform. Your role will focus on designing and executing growth-driven experiments to enhance user engagement and retention while collaborating with cross-functional teams. The ideal candidate has strong expertise in React and TypeScript, and a commercial mindset that translates into actionable insights that drive business objectives. Join a company that values experimentation and measurable impact.

Qualifications

• Strong experience with React and TypeScript, owning web products end-to-end.
• Experience with frontend platforms or product-facing web applications.
• Ability to influence business metrics through features and experiments.

Responsibilities

• Own the frontend web platform, ensuring scalable and high-performance experiences.
• Design growth-focused experiments to improve retention and engagement.
• Collaborate with product and marketing to create actionable features.

Skills

React

TypeScript

Frontend development

Commercial mindset

Tools

GraphQL

Go

Kubernetes

GCP

Job description

About Eucalyptus

We’re on a mission to make good health last a lifetime. More than 1 billion people live with obesity worldwide, driving preventable chronic conditions. We’re here to build better long-term care.

Euc is the company behind Juniper, one of the world’s largest weight-management programs combining GLP-1 medication with personalised nutrition, movement support, and clinician-led care from prescribers, nurses, health coaches, pharmacists, and dietitians. Our published clinical research shows that our combined clinical and behavioural approach helps patients lose significantly more weight during their treatment with Juniper by four times.

Our Growth Story:

• 130% YoY revenue growth and a 90% reduction in cash burn, with $100M+ raised from investors including BOND, NewView, Blackbird and Airtree.
• Supported over 350k patients living with obesity across our 5 markets
• Received selective NICE endorsement to provide services to the NHS.
• Tailored our offering to thousand of patients in Germany and Japan

Own our Frontend Web, run growth experiments, and shape product impact

At Eucalyptus, we’re on a mission to make healthcare simpler, safer, and more accessible. Patients face friction when navigating care, and the Growth squad focuses on building frontend web experiences that directly move key metrics—retention, engagement, and conversions—while shaping the overall patient experience.

One of the key initiatives you’ll contribute to is experimentation across the frontend platform, designing and testing features that influence how patients engage with our services. This is a chance to drive measurable impact and shape best practices for the platform used across the business.

Our stack: React, React Native, GraphQL Federation, Go, TypeScript, gRPC, Pub/Sub, Kubernetes, GCP.

The impact you will have

• Take ownership of the frontend web platform, ensuring scalable, polished, high-performance experiences
• Design and deliver growth-focused experiments that improve retention, engagement, and conversions
• Collaborate closely with product and marketing to translate insights into actionable features
• Influence frontend best practices across the team and mentor teammates

Who succeeds here

You’ll likely succeed if you:

• Have strong React & TypeScript experience, with full ownership of web products
• Are experienced working on frontend platforms or product-facing web apps
• Have a commercial mindset, understanding how features and experiments impact business metrics
• Thrive in autonomous, senior-level roles, able to take ownership end-to-end

You don’t need to tick every box — if this role excites you, we’d still love to hear from you.

Nice to haves

• Growth-focused engineering experience
• Experience with GraphQL

This is a senior, high-autonomy role where engineers get to own the frontend experience, define best practices, and directly influence growth metrics. You’ll work in a team that values experimentation, collaboration, and measurable impact, shaping features that truly move the needle for patients and the business.

If driving growth through product engineering and shaping high-impact patient experiences sounds exciting, we’d love to hear from you.