Frontend Engineer

• Hybrid, minimum two days a week in the office

Mid-level

• London, Old Street
• Hybrid, minimum two days a week in the office

You’ll build the frontend of how people discover, understand, and start with Thriva: the onboarding and quiz experience, the core purchase funnel, and the experiments that make both better. It's the highest-traffic, highest-leverage surface we have, and it's an area you can grow into owning.

You won’t just build the change and hand it off. You'll help decide what to test, build it, instrument it, read the result, and be part of the call on whether it ships. Engineers here take part in the experimentation programme rather than deliver for it.

You’d join a squad of four: one other engineer, a product designer, and a data analyst. You’ll be working closely with the team to have a rapid understanding of the experiments you’ve built. Engineering is around ten people in total, and our CTO founder still writes code.

Because we’re small, work doesn’t always arrive fully specced. Often you’ll work with your designer on the solution; sometimes the details will be yours to decide. If having a real say in what gets built appeals to you, that's the best part of the job. If you’d rather work to a tight spec, this probably isn’t the role.

The stack is a Nuxt/Vue frontend against a Ruby on Rails monolith. You’ll spend most of your time in the frontend and drop into Rails when a change needs backend support. We’ll help you get there if Rails is new to you. AI tooling is part of how we work rather than a side experiment, and working out where it earns its place is part of the job.

About Thriva

At Thriva, we’re on a mission to close the gap between lifespan and healthspan. While people are living longer, they’re also spending more years in poor health. We help people live better now, and for longer, with proactive at-home blood testing, connected wearables, doctor-reviewed results, and personalised actions backed by evidence. Growing that number means getting someone from “I’m curious about my health” to “I’ve taken a test, and I understand what it means” — without friction, and without overselling. That journey is where this role sits.

What you’ll work on

• The quiz and onboarding flow every new user moves through, and the purchase funnel from first landing to a completed order Experiments end to end: variants behind flags, tests designed to answer a real question, honest write-ups when the answer is “no change” or “worse”
• The shared component library, built with design rather than around it
• Rails changes where a feature needs them, with support until you’re comfortable there
• Many more interesting challenges as we scale

How you’ll grow here

You’ll work alongside an experienced engineer who’ll review your code, pair when it’s useful, and be who you learn the codebase from. Rails will be new to plenty of strong candidates and we’ll support you into it.

Within the first six months we’d expect you to be owning part of the onboarding and funnel work rather than just contributing to it. We back people who get proactive early.

From there the scope is wider than this role. There’s frontend across the whole business: consumer web, mobile, and our B2B products. The frontend group is small relative to all of that, so there’s real scope to work across more of it over time. We’re also building AI into the product properly: personalised recommendations, insights, and behaviour change. It’s new ground and there’s room to help shape it.

About You

This is a mid-level role. You’ve got a solid stretch of production frontend work behind you, you can take a well-shaped problem and run with it.

• Solid experience building production frontends with a modern component framework: Vue, React, Svelte, or similar. Transferable skills matter more to us than a specific framework.
• Real care for user-facing detail: how a page loads, how a form behaves when it fails, how a flow feels on a slow phone
• Comfortable using data to inform decisions. You’d rather measure than guess.
• Happy to work across the stack. Rails experience isn’t needed; an appetite for learning it is.
• Good working knowledge of AI tooling, or a real appetite to get there

Nice to have, genuinely optional:

Nuxt/Vue or Rails specifically, A/B testing or feature flagging tools (we use GrowthBook), design systems or Storybook work.

What we offer

• Salary benchmarked against London market data and reviewed annually - we’ll share the band on our first call.
• Equity options.
• Hybrid working from our Old Street office.
• Annual learning budget.
• Private health cover with BUPA.
• Enhanced parental leave.
• Free Thriva testing, of course.