Senior Backend Engineer (Python)

London, United Kingdom | On-site | Full-time Build the AI infrastructure powering the future of financial services. This isn't a typical backend engineering role. We're looking for a Senior Backend Engineer who thrives on solving complex technical challenges at scale. You'll build the backend systems that enable AI applications to process highly sensitive financial data securely, reliably, and at enterprise scale. If your experience is primarily focused on small web applications, basic CRUD APIs, or you haven't built distributed backend systems in production, this role is unlikely to be the right fit. We're looking for engineers who enjoy designing scalable architecture, optimizing performance, and building software that operates under demanding security and reliability requirements. The OpportunityJoin a fast-growing, venture-backed AI company transforming how financial institutions work. You'll play a key role in designing the backend infrastructure behind an enterprise AI platform used by investment firms, private equity, consulting businesses, and other financial organisations. Working alongside machine learning engineers, infrastructure specialists, and product teams, you'll help build systems capable of processing massive volumes of financial data while maintaining exceptional performance, reliability, and security. As one of the senior members of the engineering team, you'll influence technical architecture, mentor other engineers, and help establish engineering best practices as the company continues to scale globally. What You'll Be DoingDesign, build and maintain scalable backend services using Python.Develop high-performance APIs supporting AI-powered enterprise applications.Architect and optimise data pipelines processing large financial datasets.Design efficient PostgreSQL database schemas and optimise complex queries.Collaborate closely with Machine Learning Engineers to deploy AI models into production.Build secure, highly available distributed systems with enterprise-grade reliability.Improve application performance, scalability and system observability.Lead technical design discussions and architectural decisions.Troubleshoot production issues and continuously improve platform stability.Mentor engineers through code reviews and technical guidance.Contribute to engineering standards, documentation and development best practices. What We're Looking ForRequired7+ years of professional backend engineering experience.Expert-level Python development experience.Strong experience with modern Python web frameworks (FastAPI, Django, Flask or similar).Deep knowledge of PostgreSQL and relational database design.Experience building scalable REST APIs and backend services.Strong understanding of distributed systems and scalable architecture.Experience working with cloud platforms (Azure preferred, AWS or GCP also considered).Experience designing production-grade data pipelines.Strong understanding of software architecture and engineering best practices.Bachelor's degree in Computer Science, Engineering, or equivalent practical experience. Nice to HaveExperience deploying Machine Learning models into production.Exposure to AI infrastructure or LLM-powered applications.Experience working in fintech or enterprise SaaS.Knowledge of SOC 2, GDPR, or financial industry compliance.Experience with containerisation and Kubernetes.CI/CD and Infrastructure-as-Code experience.Familiarity with event-driven architectures and message queues. You'll Thrive Here If YouEnjoy solving technically difficult engineering problems.Take ownership of systems from design through production.Care deeply about code quality, scalability and reliability.Like working in fast-moving startup environments.Can balance speed with long-term technical excellence.Enjoy collaborating across engineering, infrastructure and AI teams. What You'll ReceiveCompetitive salary.Meaningful equity package.Direct collaboration with the founding team.Opportunity to influence technical architecture from an early stage.Work on cutting-edge AI products solving real enterprise challenges.Join a company backed by significant institutional investment with ambitious global growth plans. Why This Role?If you're looking for another backend role maintaining legacy systems, this isn't it. If you want to build the infrastructure behind next-generation AI products used by some of the world's leading financial institutions—and help shape the technical direction of a rapidly growing engineering team—this is the opportunity to do it. Fill in the form, we will contact you...