Senior Software Developer

Are you a senior backend engineer who thrives on distributed systems, clean architecture, and complex data problems? At ONYX Insight, we re looking for a Senior Software Developer (Contractor) to make an immediate impact on our core platform, a sophisticated distributed system processing data from wind turbines around the world. This is not a typical SaaS CRUD role. You ll work across a distributed architecture including asynchronous messaging, worker processes, and data ingestion pipelines. Frontend exposure is a bonus, not a requirement.

Key Responsibilities

• Backend Delivery: Implement robust, well-tested C# .NET services following clean architecture principles 6 domain logic, data access, messaging, and background processing.
• Distributed Systems: Contribute to service boundary design, asynchronous messaging flows, and worker processes within our modular monolith, with an eye on future decomposition.
• Data Pipelines: Build and maintain backend ingestion flows that sanitise, standardise, and process high-volume sensor data reliably and at scale.
• Code Quality: Write clean, well-tested code with strong unit and integration coverage. You care about correctness, not just delivery.
• Collaboration & Deployment: Support frontend engineers with clean API contracts, and contribute to our CI/CD pipeline and artifact-based deployment process.

Ideally, you ll have/be

• Deep, commercial C# .NET experience (5+ years) 6 comfortable with clean architecture, SOLID principles, and building maintainable systems at scale.
• Solid experience with distributed systems and async patterns 6 service buses, message queues, background workers, and event-driven architecture. You understand the tradeoffs, not just the tooling.
• Experience building data ingestion or processing pipelines 6 handling high-volume, real-world data with a focus on reliability and fault tolerance.
• Strong PostgreSQL skills 6 schema design, migrations, and efficient queries against complex data models.
• A genuine testing culture 6 unit and integration tests written as standard, with an understanding of what makes a test suite valuable.
• Familiarity with AWS and how backend services are deployed and monitored in production.
• Experience with modular or service-oriented architectures 6 you appreciate well-defined boundaries and can work pragmatically within a monorepo.
• A contractor mindset: self-directed, fast to ramp up, and able to deliver independently 6 while communicating clearly when things need to be challenged.
• Some React or TypeScript exposure is useful, but frontend delivery is not an expectation of this role.