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

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