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

About The RoleWhat 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: AlignerrType: Hourly ContractLocation: RemoteCommitment: 20–40 hours/weekWhat You'll DoDesign, build, and optimize high-performance C# systems supporting AI data pipelines and evaluation workflowsDevelop full-stack tooling and backend services for large-scale data annotation, validation, and quality controlImprove reliability, performance, and safety across existing C# codebasesCollaborate with data, research, and engineering teams to support model training and evaluation workflowsIdentify bottlenecks and edge cases in data and system behavior — then implement scalable, production-ready fixesParticipate in synchronous design and code reviews to iterate on system architecture and implementation decisionsWho You AreNative or fluent English speaker with clear written and verbal communication skillsExperienced full-stack developer with a strong systems programming background3–5+ years of professional experience writing production C# with a focus on modern standardsDeep understanding of performance optimization, concurrency (threading, atomics), and memory safetySelf-directed and reliable — able to commit 20–40 hours per week and deliver without hand-holdingNice to HavePrior experience with data annotation, data quality, or evaluation systemsFamiliarity with AI/ML workflows, model training, or benchmarking pipelinesExperience with distributed systems or developer toolingBackground in C++17/C++20 or other systems-level languagesWhy Join UsWork on real production systems used by leading AI research labsFully remote — work from anywhere, on a schedule that suits youFreelance autonomy with the structure of impactful, technically demanding workContribute to infrastructure that directly influences how next-generation AI models are built and evaluatedPotential for ongoing work and contract extension as new projects launch