Senior Full Stack Engineer

Senior Full Stack Engineer – Backend / APIs / AI Location: London Working Pattern: Hybrid Salary: Up to £85,000 + 20% Bonus The Opportunity We’re working with a major global financial services organisation that is investing heavily in modernising the way data science, analytics and AI capabilities are delivered across the business. The organisation has already built a growing portfolio of data-driven applications and is now creating a dedicated engineering capability to provide the backend foundations, APIs and integration layers that sit behind them. This is a newly created senior engineering position with significant scope to influence architecture, engineering standards and how applications consume data and AI capabilities across the organisation. You'll work closely with data scientists, application engineers, architects and wider technology teams to build the technical backbone that enables these applications to scale. What You'll Be Doing Design, build and maintain robust backend services that sit behind data-driven applications.Develop high-quality REST and GraphQL APIs for downstream consumers.Build integration and middleware layers connecting applications, data platforms and enterprise systems.Develop and maintain Model Context Protocol (MCP) servers and services that allow AI agents and applications to consume organisational capabilities.Own the serving layer for machine learning and data science outputs.Work closely with data scientists to productionise and expose models and analytical capabilities.Help establish reusable patterns for how applications consume data, models and enterprise services.Design secure, scalable and maintainable APIs suitable for an enterprise environment.Contribute to architectural decisions around application integration and service design.Help establish engineering standards, governance and best practice within a developing engineering function.Work closely with technology teams to integrate different platforms and technology stacks.Mentor and provide technical guidance to other engineers and data professionals.Help transition existing data science-built applications towards a more sustainable engineering model. What We're Looking For We're looking for a senior backend-focused engineer who is comfortable operating across application development, APIs, integrations and modern AI/data technologies. You'll ideally have: Strong commercial experience with Python.Strong experience building production-grade REST APIs.Experience with FastAPI, Flask or similar Python web frameworks.Experience designing and developing integrations between applications and enterprise systems.Strong understanding of API design, authentication, security and governance.Experience working with GraphQL would be beneficial.Practical experience with Model Context Protocol (MCP) is highly desirable.Experience working with machine learning models, AI services or data science outputs.Experience with Databricks or another modern data platform.Good understanding of cloud-based application architecture.Experience working with distributed systems, middleware or service-oriented architectures.Strong software engineering fundamentals, including testing, version control, CI/CD and production support. The Ideal Background This role would suit someone who has progressed beyond simply writing Python services and is comfortable taking ownership of how backend capabilities are designed, exposed and consumed across an organisation. Experience within a large enterprise, financial services organisation or another highly regulated environment would be particularly valuable. You'll need to be comfortable navigating governance, security and architectural standards while still being able to move quickly and make pragmatic engineering decisions. Most importantly, we're looking for someone who can act as a technical SME and help shape the direction of the capability rather than someone looking for their next step into senior engineering. Why Join? This is a chance to join at the beginning of a significant engineering transformation. You'll have the opportunity to: Build backend capabilities from the ground up.Work at the intersection of software engineering, data and AI.Develop APIs and MCP services that will be consumed across the organisation.Help productionise machine learning and data science capabilities.Influence architecture and engineering standards.Work on genuinely greenfield problems rather than maintaining a mature, established platform.Collaborate with senior stakeholders and technology teams across the organisation.Mentor existing engineers and data professionals.Play a key role in a multi-year technology transformation.