Senior Backend Engineer (C#) - AI Data Platform

Seattle

**Senior Backend Engineer (C#) --- AI Data Platform** **About The Role** What if your C# engineering skills could directly shape the infrastructure powering the world's most advanced AI systems? We're looking for a Senior C# Engineer to design and build the data pipelines, annotation tooling, and evaluation infrastructure that leading AI labs depend on to train and improve next-generation models. This is a fully remote, flexible contract role working on real production systems at the frontier of AI development. If you're a seasoned backend engineer who wants meaningful, high-impact work --- this is it. * Organization: Alignerr * Type: Hourly Contract * Location: Remote * Commitment: 20--40 hours/week **What You'll Do** * Design, build, and optimize high-performance C# systems supporting AI data pipelines and model evaluation workflows * Develop backend services and tooling for large-scale data annotation, validation, and quality control * Improve reliability, performance, and safety across existing C# codebases * Collaborate with data, research, and engineering teams to support model training and evaluation infrastructure * Identify bottlenecks and edge cases in data and system behavior, then implement scalable, production-ready fixes * Participate in synchronous design reviews to iterate on architecture and implementation decisions **Who You Are** * Native or fluent English speaker with clear written and verbal communication skills * 5+ years of professional experience building scalable backend services in C# * Strong systems programming background with full-stack development experience * Deep expertise in modern frameworks for RESTful APIs and RPC services * Experienced integrating cloud-native data services and orchestrating workflows via message bus architectures * Able to commit 20--40 hours per week with reliability and consistency **Nice to Have** * Prior experience with data annotation, data quality pipelines, or model evaluation systems * Familiarity with AI/ML workflows, model training, or benchmarking infrastructure * Background in distributed systems design or developer tooling **Why Join Us** * Work directly on cutting-edge AI projects alongside the world's leading research labs * Fully remote and flexible --- structure your hours around your life * Freelance autonomy with the substance of high-impact, technically challenging work * Contribute to infrastructure that shapes the future of AI at a foundational level * Potential for ongoing engagement and expanded scope as new projects launch