Overview
In this Backend Engineer role you will design multi-tenant data and workflow services in Python and FastAPI, and bridge between a Java/Spring core and Python AI services. You will work with an enterprise audience, ensuring permissions, audit trails, and safe AI outputs. You’ll join a UK core engineering team reporting to the Head of Engineering, delivering resilient services through CI/CD with a cross-border delivery organization. This is an opportunity to lay the foundations of an enterprise-grade platform for a sizable, growth-focused market.
Responsibilities
- Design REST and asynchronous services in Python 3.11+ with FastAPI
- Work at Java/Spring boundaries with PostgreSQL and async SQLAlchemy persistence
- Implement tenant isolation, RBAC, and configuration
- Version and evolve contracts between core and AI services
- Maintain unit and integration tests with pytest and pytest-asyncio
- Expose performance and reliability metrics with OpenTelemetry, logs, and alerts
- Ensure authentication, authorization, secrets, input validation, and audit trails
- Deploy and operate on AWS using EKS/ECS, RDS and S3 through Jenkins gates
- Improve queries, caching, throughput, and right-sizing
- Build queueing, rate limits and cost-aware orchestration for model calls
Key requirements
- 5+ years in backend engineering for production SaaS or platform systems
- Experience with multi-tenant or enterprise systems including isolation, permissions, and auditability
- Strong Python with FastAPI (or similar) and solid SQL/PostgreSQL
- Ability to work across Java/Spring service boundaries
- Production AWS experience, Git, CI/CD and Linux
- Experience with AI coding tools (Cursor or Claude Code)
- Degree in engineering, computer science or related field, or equivalent experience
- pace and accuracy
- cross-functional collaboration
- problem-solving under high-stakes constraints
- Python 3.11+
- FastAPI
- PostgreSQL
Backend Engineer in London employer: Oscar
Join a dynamic and innovative software and Business Intelligence organisation in Hertford, where you'll thrive in a hybrid work environment that promotes flexibility and collaboration. As a Data Consultant, you'll enjoy a varied role with opportunities for professional growth, including managing projects from inception to deployment and engaging with a European customer base. The company fosters a supportive culture that values continuous learning and offers exposure to exciting industry events, making it an excellent employer for those seeking meaningful and rewarding work.
