Senior C# Full-Stack Engineer — AI Data & Infrastructure

Senior C# Full-Stack Engineer — AI Data & Infrastructure About the Role What if your C# expertise could directly shape the systems that power the world's most advanced AI models? We're looking for a Senior C# Full-Stack 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 AI. This is a fully remote contract role working on real production systems — not toy problems. You'll collaborate with data, research, and engineering teams at the frontier of AI development, solving genuinely hard infrastructure and systems challenges at scale. 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, and implement scalable, production-ready fixes Participate in synchronous design reviews to iterate on system architecture and implementation decisions Who You Are Full-stack developer with a strong systems programming background and deep C# expertise 3–5+ years of professional experience writing production C# code with a focus on modern standards Solid understanding of performance optimization, concurrency (threading, atomics), and memory safety Clear and precise written and verbal communicator — you can articulate technical decisions confidently Native or fluent English speaker Available to commit 20–40 hours per week consistently Nice to Have Prior experience with data annotation, data quality, or evaluation systems Familiarity with AI/ML workflows, model tr