Posted Sep 30, 2026

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

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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