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 — working on real production systems with genuine, measurable impact.This is a fully remote contract role with flexible hours. If you're a sharp systems thinker who loves solving hard infrastructure problems, this is the kind of work that will actually push you.Organization: AlignerrType: Hourly ContractLocation: RemoteCommitment: 20–40 hours/weekWhat You'll DoDesign, build, and optimize high-performance C# systems supporting large-scale AI data pipelines and evaluation workflowsDevelop full-stack tooling and backend services for data annotation, validation, and quality control at scaleImprove reliability, performance, and safety across existing C# codebases — hunt down bottlenecks and ship scalable fixesCollaborate directly with data, research, and engineering teams to support model training and evaluation workflowsIdentify edge cases and systemic issues in data and system behavior and implement robust solutionsParticipate in synchronous design reviews to iterate on architecture and implementation decisionsWho You AreFull-stack developer with a strong systems programming background and 3–5+ years of professional C# experienceConfident writing production-quality code with a focus on modern C# standards and best practicesDeep understanding of performance optimization, concurrency (threading, atomics), and memory safetyClear, precise written and verbal communicator — you can articulate technical decisions without hand-wavingSelf-directed and reliable when working remotely with minimal supervisionNative or fluent English speakerAble to commit 20–40 hours per week on a consistent basisNice to HavePrior experience with data annotation, data quality pipelines, or AI evaluation systemsFamiliarity with AI/ML workflows, model training, or benchmarking infrastructureExperience with distributed systems or developer toolingBackground working in fast-moving research or applied ML environmentsWhy Join UsWork directly with leading AI labs on cutting-edge production systems — not toy projectsFully remote and flexible — structure your work around your lifeFreelance autonomy with the focus and momentum of high-impact engineering workCollaborate with world-class data, research, and engineering teams pushing the frontier of AIPotential for ongoing work and contract extension as projects scale