Role summary: A product-minded senior frontend engineer who thrives in fast-growth environments, owns features (and their quality) end-to-end, and uses agentic development workflows to ship faster. Works closely with product and design, not just executing tickets.
Responsibilities: Work closely with the Product team to build out core applications for both internal and external users.
Evaluation criteria (in priority order):
1. Fast-growth / high-performance startup or scaleup experience (highest weight)
Has worked at a Series A/B (or comparable) startup through a period of rapid scaling, ideally not just a large, stable org.
Comfortable with ambiguity, shifting priorities, and shipping under pressure without over-engineering.
Signals: early/founding engineer roles, "first N engineers," ownership of significant surface area, demonstrable velocity. Be wary of CVs showing only big-company or agency/consultancy backgrounds.
2. Strong agentic workflows / development optimisation
Actively uses AI coding agents (Claude Code, Cursor, etc.) as a core part of how they work, not as an occasional aid.
Thinks about optimising their own and the team's development workflow - tooling, automation, spec-driven development.
Signals: mentions of agentic/AI-native development, internal tooling, DX improvements, side projects built with agents, relevant OSS contributions (MCP, agent frameworks). Recency matters - this should be current, not aspirational.
3. Strong product engagement / design collaboration
Engages with the "why," contributes to product decisions, and pushes back constructively rather than waiting for fully-specced tickets.
Collaborates directly with designers; comfortable with Figma handoff and translating design intent into polished UI.
Signals: product-led teams, mentions of shaping features, user-facing ownership, design-system or UX-quality work.
4. React experience
Solid, current production React. Adjacent modern stack (TypeScript, Next.js) is a plus.
Note: lowest-weighted of the ranked criteria - a strong agentic, product-minded scaleup engineer with a slightly different framework background may still be worth considering.
Ownership of quality (baseline expectation):
Used to owning their own testing and quality - writes and maintains their own tests, doesn't rely on a separate QA function to catch issues.
Signals: TDD/testing discipline, mentions of test coverage ownership, "you build it, you run it" cultures.
Disqualifiers / flags:
Cannot commute to London.
Purely backend or infrastructure focus with no frontend ownership.
No evidence of any of the top three criteria.
Levels is an equal opportunity employer. We welcome applications from all qualified candidates regardless of background, and we're committed to building a diverse and inclusive team.
Skills Required
- Experience at a fast-growth startup/scaleup (Series A/B or comparable) through rapid scaling
- Active use of AI coding agents and agentic development workflows (e.g., Claude Code, Cursor)
- Strong product engagement and collaboration with design, comfortable with Figma handoffs
- Production React experience
- Ownership of testing and quality (TDD, writing and maintaining tests)
- Ability to commute to London (on-site/nearby)
- Frontend ownership; not a purely backend/infrastructure role
- TypeScript
- Next.js
- Experience improving tooling, automation, and developer experience (internal tooling, DX)
What We Do
Levels is a metabolic health company that combines continuous glucose monitoring, wearable and lab data, and an app-driven platform to give personalized feedback on how diet, sleep, and activity affect metabolic function. The company provides CGM access, biomarker testing, habit tracking, and clinician support to help users optimize energy, appetite, and long-term metabolic health.
