Senior Backend Engineer (C#) - AI Data Platform

New York

**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 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 scheduling --- and the work is anything but routine. You'll be embedded in real production systems, solving hard engineering problems at the intersection of scale, performance, and AI. * Organization: Alignerr * Type: Hourly Contract * Location: Remote * Commitment: 20--40 hours/week **What You'll Do** * Design, build, and optimize high-performance C# systems supporting AI data pipelines and evaluation workflows * Develop backend services and full-stack tooling for large-scale data annotation, validation, and quality control * Improve reliability, performance, and safety across existing C# codebases used in production AI systems * 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, elegant fixes * Participate in synchronous design reviews to iterate on architecture and implementation decisions **Who You Are** * Native or fluent English speaker with clear written and verbal communication skills * 5+ years of professional experience building scalable backend services in C# * Strong systems programming background with full-stack development experience * Deep mastery of modern frameworks for RESTful APIs and RPC services for inter-service communication * Experienced integrating with cloud-native data services and orchestrating workflows via message bus architectures * Self-directed and reliable --- you can commit to 20--40 hours per week and deliver without hand-holding **Nice to Have** * Prior experience with data annotation, data quality pipelines, or evaluation systems * Familiarity with AI/ML workflows, model training, or benchmarking pipelines * Experience with distributed systems design or developer tooling **Why Join Us** * Work on cutting-edge AI infrastructure alongside world-class research labs * Fully remote and flexible --- work on your own schedule from anywhere * Freelance autonomy with the substance of genuinely high-impact engineering work * Contribute to systems that directly influence how next-generation AI models are built and evaluated * Potential for ongoing work and contract extension as new projects launch