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

About The Role What if your C# expertise could directly shape the infrastructure powering the next generation of AI? We're looking for a Senior C# Full-Stack Engineer to build and optimize the data pipelines, annotation tooling, and evaluation systems that leading AI labs depend on every day. This is a fully remote contract role with meaningful technical depth and real production impact. You'll work alongside data, research, and engineering teams at the frontier of AI development — solving hard problems 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 — then implement scalable, production-ready fixes • Participate in synchronous design and code reviews to iterate on system architecture and implementation decisions Who You Are • Native or fluent English speaker with clear written and verbal communication skills • Experienced full-stack developer with a strong systems programming background • 3–5+ years of professional experience writing production C# with a focus on modern standards • Deep understanding of performance optimization, concurrency (threading, atomics), and memory safety • Self-directed and reliable — able to commit 20–40 hours per week and deliver without hand-holding 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 C++17/C++20 or other systems-level languages Why Join Us • Work on real production systems used by leading AI research labs • Fully remote — work from anywhere, on a schedule that suits you • Freelance autonomy with the structure of impactful, technically demanding work • Contribute to infrastructure that directly influences how next-generation AI models are built and evaluated • Potential for ongoing work and contract extension as new projects launch