Software Engineer (C#) - Internal Tooling

Seattle

**Software Engineer (C#) --- Internal Tooling (AI Infrastructure)** **About The Role** What if your C# skills could directly shape the infrastructure powering next-generation AI systems used by millions of people? We're looking for a senior full-stack C# engineer to build and optimize the internal tooling, data pipelines, and evaluation systems that leading AI labs depend on every day. This is a fully remote contract role with flexible hours. You'll work on real production systems --- not toy projects --- alongside data, research, and engineering teams at the frontier of AI development. * 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 evaluation workflows * Develop full-stack tooling and backend services 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 workflows * Identify bottlenecks and edge cases in data and system behavior, then implement scalable fixes * Participate in synchronous design reviews to iterate on architecture and implementation decisions **Who You Are** * Native or fluent English speaker with strong written and verbal communication skills * Full-stack developer with a solid systems programming background * 3--5+ years of professional experience writing production-grade C# * Experienced with interoperability scenarios --- invoking Python ML models from .NET, wrapping native libraries, or similar cross-language integrations * Skilled at designing robust harnesses for benchmarking and evaluating system performance * Able to commit 20--40 hours per week with reliability and consistency **Nice to Have** * Prior experience with data annotation, data quality, or evaluation systems * Familiarity with AI/ML workflows, model training, or benchmarking pipelines * Experience with distributed systems or developer tooling * Background in research infrastructure or high-throughput data processing **Why Join Us** * Work on cutting-edge AI projects alongside leading research labs * Fully remote and flexible --- work when and where it suits you * Freelance autonomy with the structure of meaningful, high-impact engineering work * Make a direct, tangible contribution to the infrastructure driving the next generation of AI * Potential for ongoing work and contract extension as new projects launch