Role summary:
A backend engineer who thrives in fast-growth environments, owns services end-to-end, and uses agentic development workflows to ship faster. Will work on the core applications powering the business.
Responsibilities:
Develop and own our core applications - CRM and finance services - for 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. Python / FastAPI (must-have)
Strong, current production Python with FastAPI specifically. This is a hard requirement, not a nice-to-have.
Signals: API design, async Python, building and maintaining services in production. Adjacent data/persistence experience (SQL, ORMs) a plus.
3. 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.
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: testing discipline, test coverage ownership, "you build it, you run it" cultures.
Disqualifiers / flags:
No FastAPI / weak Python.
Based outside Europe.
Purely frontend focus with no backend service ownership.
No evidence of the scaleup or agentic 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
- Strong, current production Python with FastAPI (specific)
- Experience at a fast-growth startup/scaleup (Series A/B or comparable)
- Active use of agentic/AI coding agents and agentic development workflows
- End-to-end backend service ownership (CRM/finance or similar)
- Owns testing and quality (writes and maintains tests; "you build it, you run it")
- Familiarity with SQL and ORMs
- Based in Europe / UK (candidates outside Europe are disqualified)
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.
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