Senior Python Backend Developer - API Design at iO Associates, England, £325 per day

Role: Senior Python Backend Developer - API Design (Fully remote Part-time contract)
Rate: £325 p/d (Outside IR35)
Duration: 15 June 2026 till end of December 2026
Workload: 110 days billable allowance (To be allocated during contract period)
Location: 100% Fully Remote (Cloud-based collaboration platform)
Eligibility: Candidates MUST be a national of a NATO member country.

The Role

We are seeking an expert Senior Python Backend Developer to design, build, and operate scalable services and data pipelines powering maritime geospatial and temporal analytics. This is a hands-on engineering role with strong end-to-end feature ownership, you will be translating complex domain models into clean, testable code using Domain-Driven Design (DDD), defining clear bounded contexts, and building production-grade APIs.

What You'll Be Doing:

• API & Microservices: Developing asynchronous, production-grade APIs and microservices using FastAPI.
• Graph Architecture: Integrating and optimizing graph-centric use cases using Neo4j and Cypher query modeling.
• Data Pipelines: Leveraging Databricks for data engineering and ML workflows.
• Feature Leadership: Leading features end-to-end-from technical discovery and design through implementation, testing, deployment, and monitoring.

What We Need From You:

• Advanced Python & FastAPI: Deep proficiency with asynchronous Python, type hints, and async best practices.
• Domain-Driven Design (DDD): Strong practical experience applying DDD principles (aggregates, bounded contexts, domain services).
• Database Expertise: Heavy hands-on experience with Neo4j (Cypher optimization) alongside strong relational SQL (PostgreSQL/SQL Server).
• Geospatial Data: Experience modeling, processing, and querying geospatial and temporal datasets.
• The Stack: Robust knowledge of Docker, event-driven systems (Kafka/MQTT), and secure coding practices (OWASP Top 10).