Senior Backend Engineer

Senior Backend Engineer — London or England remote London, UK · Permanent · Hybrid Join a team small enough that what you build is what exists, and take agentic AI features from a founder's idea to something hundreds of investment firms rely on to make real capital decisions. What you'd actually work on Building and shipping production backend services and APIs in Python (FastAPI) that power the platform's AI features, used daily by professional investors Designing and owning the orchestration layer for agentic AI capabilities: how the system plans, calls tools, and retrieves the right data at the right time Working directly with PostgreSQL and ClickHouse to enable fast, reliable data retrieval for AI-driven analysis at real scale Taking a feature from a founder's rough idea to something live in production within the same sprint, without layers of process in between Mentoring teammates and helping set engineering standards as the team grows from around seven engineers today to over thirty Making real calls on architecture and tooling rather than inheriting decisions frozen in place years ago Working closely enough with the founders that your technical judgment shapes what gets built next, not just how it gets built Where it gets technically interesting Agentic workflows and tool use sit on top of a data platform that has to stay fast and correct under real investor usage, not a demo Two different database workloads in the same system: PostgreSQL for transactional data, ClickHouse for the columnar, analytics-heavy queries behind the AI insights AI coding tools (Cursor, Claude) are part of the actual day-to-day workflow, not a side experiment A genuinely small engineering team means no one else is quietly maintaining the parts you don't touch Retrieval and embeddings work that has to hold up against messy, high-stakes private market data rather than clean public datasets What we're looking for 5 to 15 years of backend engineering experience, most of it in Python, in production environments A track record of building and personally owning APIs or services used by real customers, not just maintaining systems someone else designed Time spent at a startup or scaleup (roughly 30 to 100 people), not exclusively large corporate environments Hands-on experience shipping AI or LLM features to production: agentic workflows, RAG, or tool use Strong SQL and solid experience with PostgreSQL or an equivalent relational database A genuine preference for staying hands-on and coding day to day rather than moving toward management Based in Europe (outside France and the Nordics); if based in London, comfortable working from the office five days a week Bonus: experience with columnar databases (ClickHouse, Redshift, Snowflake) or general DevOps/infrastructure skills The company An alternative data and private market intelligence platform, giving investors real-time data and AI-driven analysis to make faster, better-informed decisions. Used by hundreds of leading VC and PE firms across Europe and beyond. Small, fast-moving engineering team of around thirty people, still shaped day to day by its founders. Equity participation (ESOP) after six to nine months. Languages: English (fluent, working language of the team) A search run by The French Sourcer, recruitment built for technical teams. Fill in the form, we will contact you...