Full-Stack Product Engineer — Growth & Data

*London · Hybrid, 2 days in office · £65,000–£80,000 + equity + benefits · Permanent
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We are partnering with an ambitious Seed stage AI startup based in London to hire their first dedicated growth hire — a builder who ships the product, reads the data, and calls the next bet.

What they do

They're building the senior AI employee for small-business owners. It plugs into the tools they already use, watches what they commit to, and drafts the work they owe — client updates, proposals, reports — from their real numbers, ready to approve. No prompting, no setup.

Small, senior team. Shipping weekly. Almost everything is still to be built, and you'd be building it.

The role

You're a full-stack engineer who is equally at home in the data. You build the feature, instrument it, query the numbers yourself, and come back with a verdict — not a dashboard for someone else to interpret.

Roughly 70% building, 30% analysis. No PM hands you a spec. You find the highest-impact bet and go.

This is a founding-level seat: you'll shape how the team builds, measures and decides, and you'll grow the function around you as the company scales.

What you'll build and own

• Product, end to end. TypeScript, React, APIs (GraphQL or REST), and the database underneath. Onboarding flows, connector fixes, CTAs, empty states — shipped in days, not sprints.
• The numbers. A clean event taxonomy in Amplitude (or similar), SQL you write yourself, and analysis the whole team trusts. A gap in the data is yours to fix, not someone else's to flag.
• Experiments that actually settle things. A/B tests behind feature flags (GrowthBook, PostHog, LaunchDarkly, Statsig) plus the statistical read — significance, sizing, guardrails.
• The activation funnel. Find where users lose momentum, form the hypothesis, ship the fix, prove it worked.
• Retention and growth loops. Lifecycle messaging and re-entry flows (Customer.io, Braze, Iterable, or your own), and the invite/seat/sharing loops that turn one user into their whole team.

What we're looking for

• A builder first. Production TypeScript and React, comfortable across the stack, writing clean reviewable code at pace.
• Genuinely analytical. You design the tracking plan, not just query it. SQL is a daily tool, not a favour you ask of someone else.
• Someone who's led. You've managed or mentored engineers, or owned a product area with people around you — and you're ready to do that again as this team grows.
• Founder instincts. You care about the business number, not the feature. Bonus if you've shipped something of your own.
• AI-native. You build with agentic coding tools daily — Claude Code, Cursor or similar — with your own workflows.
• Close to the customer. You want to talk to real users, see where they dropped off, and build the fix yourself.

Nice to have: design taste for the surfaces you ship · chat-native products (Slack, Teams) · OAuth integrations and connectors · LLM and agent products, prompt engineering, evals · Datadog or similar.

The details

• Full-time, permanent, flexible hours. Two days a week together in the London office.
• You'll need the right to work in the UK.
• Four stages: intro call → technical and product conversation → practical working session → founder conversation.

How to apply

Send your CV plus anything that shows how you think and build — GitHub, portfolio, products you've shipped, or a short note.

Excited by the role but don't match every line? Get in touch anyway.