Senior Backend Engineer (C#) - AI Data Platform

Senior Backend Engineer (C#) — AI Data Platform About The Role What if your C# expertise could directly shape the infrastructure powering the next generation of AI? We're looking for a Senior Backend Engineer to design and build the high-performance data pipelines, annotation tooling, and evaluation systems that leading AI labs depend on to train and improve their models. This is a fully remote contract role with flexible hours. You'll be working on real production systems — not toy projects — alongside data, research, and engineering teams at the frontier of AI development. Organization: AlignerrType: Hourly ContractLocation: RemoteCommitment: 20–40 hours/week What You'll Do Design, build, and optimize high-performance backend systems in C# supporting large-scale AI data pipelines and evaluation workflowsDevelop backend services and tooling for data annotation, validation, and quality control at scaleBuild and maintain RESTful APIs and RPC services for reliable inter-service communicationIntegrate with cloud-native data services and orchestrate workflows via message bus architecturesIdentify bottlenecks, edge cases, and reliability issues across existing codebases — then implement scalable fixesCollaborate with research and engineering teams to support model training, benchmarking, and evaluation workflowsParticipate in synchronous design reviews and iterate on system architecture decisions Who You Are 5+ years of professional experience building scalable backend services in C#Deep command of modern C# frameworks for RESTful APIs and RPC-based inter-service communicationExperienced integrating with cloud-native data services and message bus architecturesSystems-level thinker who can identify performance issues and architect clean, scalable solutionsClear, concise written and verbal communicator — comfortable working with cross-functional teamsNative or fluent English speakerAble to commit 20–40 hours per week consistently Nice to Have Prior experience with data annotation platforms, data quality systems, or evaluation pipelinesFamiliarity with AI/ML workflows, model training, or benchmarking infrastructureExperience with distributed systems design or developer toolingFull-stack background with frontend exposure alongside a strong backend foundation Why Join Us Work directly on cutting-edge AI projects alongside leading research labsFully remote and flexible — work from wherever you do your best workFreelance autonomy with the structure of meaningful, high-impact engineering workContribute to infrastructure that shapes how next-generation AI systems are built and evaluatedPotential for ongoing work and contract extension as new projects launch