Senior Backend Engineer

Senior Backend Engineer - Python / FastAPI | AI Agents | Data at ScaleLondon | Office based | £130k baseThe opportunity:We are working with a client who has built a profitable, fast-growing B2B data intelligence platform. Professional teams rely on it every day to find the right companies and make high-stakes decisions. The business is bootstrapped and strong year-on-year growth, with no runway pressure, so the focus is on building great product rather than chasing the next funding round.They’re hiring Senior Backend Engineers, which will double the backend team. Their two current backend engineers have supported huge product growth on their own, so this is a chance to shape the architecture of a platform that’s already working and growing quickly.What you’ll work on:AI agents in production: chat agents, scheduled agents and proactive agents that surface insights for users before they ask. Much of the product roadmap is built around this.Data at serious scale: fast queries over billions of rows in a column-oriented analytics database, alongside Postgres for application data. Performance tuning will be a real part of your week.The query engine behind the product: owning the filtering and query language layer that every user interaction depends on.Intelligent middleware that helps users navigate complex datasets with many entity types.Production APIs in Python/FastAPI that power both the client-facing product and a growing set of internal tools.Why it’s exciting:Ownership: you’ll get broad projects and the freedom to drive them, not a backlog of tickets.Impact: with a small team, your work reaches customers quickly and you’ll see it being used.AI that ships: AI is part of both the product and the engineering workflow, not a side experiment.Close collaboration: you’ll work directly with frontend, data and AI engineers.Stability: a profitable company with real customers and the freedom to make the right technical decisions.What you’ll bring:Strong Python backend experience, ideally with FastAPISolid SQL and Postgres skills, and a strong interest in query performance and how databases work under the hoodExperience building production APIs that other teams rely onA B2B SaaS background on platforms with broad functionalityA builder’s mindset: you take ownership, move quickly and are comfortable with loosely defined problemsBig bonus:Experience building with LLMs or AI agentsExperience with column-oriented databases such as BigQuery, Druid or similarComfort contributing to frontend work in TypeScript or ReactExperience leading or mentoring engineersA background in data-intensive productsIf this sounds like you, please apply for more info!