Senior C# Full-Stack Engineer — AI Data & Infrastructure
New York
**About The Role** What if your C# expertise could directly shape the infrastructure powering next-generation AI? We're looking for a Senior C# Full-Stack Engineer to build and optimize the systems that leading AI labs depend on --- from data pipelines and annotation tooling to evaluation infrastructure that influences how frontier models are trained and assessed. This is a fully remote contract role with meaningful technical challenges, real production impact, and the flexibility to work on your own terms. * 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 large-scale AI data pipelines and evaluation workflows * Develop full-stack tooling and backend services for data annotation, validation, and quality control at scale * 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, production-ready 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 * Experienced full-stack developer with a solid systems programming foundation * 3--5+ years of professional experience writing production C# code, with command of modern standards * Deep understanding of performance optimization, concurrency (threading, atomics), and memory safety (RAII, smart pointers, sanitizers) * Able to commit 20--40 hours per week with reliability and consistency * Self-directed and comfortable working in fast-moving, async-first environments **Nice to Have** * Prior experience with data annotation pipelines, data quality systems, or evaluation infrastructure * Familiarity with AI/ML workflows, model training loops, or benchmarking pipelines * Experience building distributed systems or developer tooling at scale **Why Join Us** * Work directly with leading AI labs on systems that influence how frontier models are built * Tackle genuinely hard engineering problems --- not maintenance tickets * Fully remote and flexible --- structure your week around your best work * Freelance autonomy with the substance of high-impact engineering work * Potential for ongoing contracts and expanded scope as projects grow
