The shape of the work
About the Role
We’re looking for a Frontend Engineer with strong React experience to help us shape, build, and evolve the next generation of our product. In this role, you’ll own meaningful product surfaces end-to-end — from collaborating with design and product, to building polished interfaces, to instrumenting and iterating based on data and feedback.
You won’t just be handed tasks; you’ll influence roadmaps, contribute to architecture, and have the autonomy to ship high-quality work quickly. If you thrive in environments where you’re trusted with ownership and want to see the immediate impact of what you build, this role is for you.
What You'll Do
Build responsive, high-performance user interfaces using React and modern JavaScript/TypeScript.
Own features from idea to deployment — including scopes, timelines, implementation, testing, and iteration.
Work closely with Design and Product to translate complex workflows into intuitive user experiences.
Improve performance, maintainability, and reliability across the frontend codebase.
Participate in code reviews and help uphold high engineering standards.
Shape technical decisions, contribute to architectural discussions, and champion best practices.
Collaborate with backend engineers to design effective APIs and data flows.
Iterate rapidly based on user feedback, analytics, and changing business needs.
What You'll Bring
2–5+ years of professional frontend engineering experience.
Strong proficiency in React, TypeScript/JavaScript, and modern frontend tooling.
Experience building and maintaining production-grade applications.
Ability to balance velocity with quality — knowing when to ship and when to refine.
A product-minded approach: you care about UX, polish, and user value.
Comfort working in a fast-moving, ambiguous startup environment.
Strong communication skills and a collaborative mindset.
A sense of ownership — you take pride in the features you build and maintain
Nice-to-Haves
Experience with frontend performance optimization
Familiarity with state management tools (Redux, Zustand, Recoil, etc.).
Exposure to design systems or component libraries.
Experience working cross-functionally in small teams.
Interest in shaping engineering culture and processes.
Why You’ll Love Working Here
High ownership and autonomy — you’ll directly influence what we ship and how we build.
A product that customers love, with strong early traction and a huge opportunity ahead.
A collaborative, low-ego team that values learning, quality, and impact.
Competitive compensation, equity, and benefits.
Equal Employment Opportunity and Diversity Statement
We are committed to equal employment opportunity in both principle and as a matter of policy. We will recruit, hire, train, promote, compensate and provide benefits to all applicants and employees without regard to ancestry, sex, race, color, ethnicity, national origin, gender, age, religion, religious creed, mental and/or physical disability, medical condition, military and/or veteran’s status, genetic information, marital status, sexual orientation, gender identity and/or expression, or any other basis protected by applicable federal, state and local laws. This policy applies to all recruiting, hiring, promotions, upgrades, layoffs, compensation, benefits, terminations and all other privileges, terms and conditions of employment. The firm complies fully with all federal, state and local equal employment opportunity laws.
What we offer
Salary band
Competitive
Public band. Same rate for the same role.
Equity
Meaningful
10-year exercise window from leaving date.
Plus 36 days off, six months fully paid parental leave, £2,000 learning budget, climate sabbatical every five years, private health, pension matched 8%, and a rail-first travel policy across our European studios. Read the full package →
How hiring works
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i
Intro call · 30 min
With our Head of People. Mutual scoping — your story, the role, package, anything you need to know up front.
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ii
Deep-dive conversation · 60 min
With the hiring manager. Real work in your domain, no trick puzzles. We share material 24 hours ahead so you can come prepared.
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iii
Take-home · ~3 hours, paid
A real task from our backlog. We pay £250 for your time, regardless of outcome.
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iv
Onsite · half day
London studio (or video). Walk through your take-home with the team, meet engineering and product, finish with a no-pressure lunch.
A bit about the team
You'll join a group spread across our European studios — academic backgrounds mixed with industry, peer-reviewed and opinionated. Quarterly we close ranks for a "field week"; recent ones included a co-op cocoa supplier in Ghana and a vertical farm in Lyon.
Mossroot is committed to building a team as diverse as the supply chains we work on. We particularly welcome applications from groups under-represented in climate science.