Senior Backend Engineer

My client is looking for a Senior Backend Engineer Contract may also be considered. What You Will Be Doing You'll sit at the core of their product, building the systems that make advanced AI usable in the real world. If you enjoy owning backend services end to end, care deeply about reliability and API quality in a high-impact environment, this role offers both autonomy and real impact. Requirements Backend Architecture & APIs (Primary Focus) Design and evolve scalable backend services in Python using FastAPI for high-availability, high-throughput workloads. Build well-versioned RESTful APIs aligned to OpenAPI/Swagger, with strong conventions for consistency, idempotency, and backward compatibility. Implement authentication and authorization using OAuth2/OIDC, session management, and fine-grained permissions. Design and maintain event-driven architectures and background processing pipelines (e.g. Celery, Redis Streams, Kafka) to enable scalable async workloads, retries, and fault-toler...