Founding Senior Product Engineer

Founding Senior Product Engineer Partnering with a well-backed seed-stage AI company in London, Foundation Partners are hiring for several founding Senior Engineers to a technically strong & lean Eng team, shape 'how' in addition to 'what' is built and help the company prepare for the next iteration of their scaling journey. The Role This is a full-stack product role with a backend-heavy centre of gravity. You'll own complete product slices end-to-end and you'll ship these without needing to be guided. You're not a specialist who hands off at the API boundary. You think in user outcomes and delivery units, and you're reliable: your code handles edge cases, your APIs have clean contracts, and the work you ship stays shipped. What You'll Do Own product delivery — take features from spec to production, backend-first but covering frontend and integration where needed Build and maintain backend systems — product APIs, data pipelines, and core infrastructure on our Python/FastAPI/Postgres stack Build with LLMs and agents — ship product features with significant LLM integration; contribute to the voice agent backend and information extraction systems Work across the stack — ship workable React/TypeScript frontend for product features; not a frontend specialist, but comfortable and pragmatic Collaborate with product and design — translate ambiguous requirements into concrete shipped work; be the engineer who unblocks, not the one who waits Maintain quality at speed — handle data integrity, error paths, API evolution, and operational concerns as a default, not an afterthought What We're Looking For Independent delivery - You can own and ship end-to-end product slices with minimal supervision; your track record shows features that shipped, stuck, and scaled Product trade-off judgment — you balance speed, quality, and user impact under ambiguity; you push back when something is underspecified and make pragmatic calls when it needs to ship Reliability and API discipline — you handle data integrity, error paths, idempotence, and API versioning as standard practice; production reliability is your default, not a later concern Cross-functional pragmatism — you work effectively with product and design, can unblock yourself across the stack, and ship workable frontend when that's what's needed Strong technical depth in: Python backend (FastAPI or equivalent, async patterns, Postgres, Redis) LLM integration — building products where AI is in the critical path, not bolted on API design and data modelling JavaScript/TypeScript — comfortable enough to ship frontend features and review frontend PRs Nice to Have Experience with voice agents or real-time audio pipelines Familiarity with evals, guardrails, or agent observability Familiarity with GCP / cloud infrastructure Experience in recruiting tech, marketplaces, or matching systems The Stack A modern Python stack: FastAPI, Postgres, Redis, Docker, Pydantic AI , running on GCP. Frontend in React/TypeScript. We iterate fast and keep the codebase clean. We'll offer you Above market salary Meaningful equity Full private healthcare & dental Fertility benefits & enhanced parental support Gym membership & wellness benefits LOTS of Claude tokens Regular socials, offsites and an annual trip MacBook Pro + team kit "Whatever you need" approach to tools and support Department Product & Engineering Roles Locations London HQ Remote status Hybrid About Foundation Partners A People team built for ambitious businesses The old model for People & Talent doesn’t work for today's businesses. We've built a better one. Traditionally, early-stage Founders had two options: handle People & Talent themselves, losing precious time they should be spending on product or go-to-market, or hire a generalist, expected to cover everything from culture to recruitment to performance. We offer a more impactful alternative: A fully flexible, fractional People & Talent team with specialist skillsets and hands-on delivery, ready to start driving impact for your business in weeks, not months. Founded in 2023 Co-workers 28