Senior C# Full-Stack Engineer — AI Data & Infrastructure
About The Role What if your C# expertise could directly shape the infrastructure powering the world's most advanced AI systems? 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 to train and improve next-generation models. This is a fully remote, flexible contract role for an experienced engineer who wants to work on real production systems at the frontier of AI — not just maintain legacy code, but architect meaningful infrastructure that matters. Organization: Alignerr Type: Hourly Contract Location: Remote Commitment: 20–40 hours/week
What You'll Do
Design, build, and optimize high-performance C# systems that support 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 used in production AI environments Collaborate closely 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, robust fixes Participate in synchronous design reviews to iterate on architecture and implementation decisions Who You Are Full-stack developer with a strong systems programming background and deep command of C# 3–5+ years of professional experience writing production-grade C# code, with familiarity with modern standards Solid grounding in performance optimization, concurrency (threading, atomics), and memory safety Native or fluent English speaker with clear written and verbal communication skills Self-directed and reliable — able to commit 20–40 hours per week and deliver consistently without hand-holding Comfortable navigating complex codebases and making principled architectural decisions under real constraints
Nice to Have
Prior experience with data annotation platforms, data quality systems, or evaluation infrastructure Familiarity with AI/ML workflows, model training pipelines, or benchmarking systems Experience building distributed systems or developer tooling at scale Background working alongside research or applied AI teams
Why Join Us
Work at the frontier of AI — your code will directly influence how the world's leading models are built and evaluated Fully remote and flexible — structure your hours around your life, not the other way around Collaborate with world-class research and engineering teams on genuinely hard problems Freelance autonomy with the substance of high-impact, technically demanding work Potential for ongoing work and contract extension as projects evolve and expand