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: Alignerr
• Type: Hourly Contract
• Location: Remote
• Commitment: 20–40 hours/week

• Design, build, and optimize high-performance backend systems in C# supporting large-scale AI data pipelines and evaluation workflows
• Develop backend services and tooling for data annotation, validation, and quality control at scale
• Build and maintain RESTful APIs and RPC services for reliable inter-service communication
• Integrate with cloud-native data services and orchestrate workflows via message bus architectures
• Identify bottlenecks, edge cases, and reliability issues across existing codebases — then implement scalable fixes
• Collaborate with research and engineering teams to support model training, benchmarking, and evaluation workflows
• Participate in synchronous design reviews and iterate on system architecture decisions

• 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 communication
• Experienced integrating with cloud-native data services and message bus architectures
• Systems-level thinker who can identify performance issues and architect clean, scalable solutions
• Clear, concise written and verbal communicator — comfortable working with cross-functional teams
• Native or fluent English speaker
• Able to commit 20–40 hours per week consistently

• Prior experience with data annotation platforms, data quality systems, or evaluation pipelines
• Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
• Experience with distributed systems design or developer tooling
• Full-stack background with frontend exposure alongside a strong backend foundation

• Work directly on cutting-edge AI projects alongside leading research labs
• Fully remote and flexible — work from wherever you do your best work
• Freelance autonomy with the structure of meaningful, high-impact engineering work
• Contribute to infrastructure that shapes how next-generation AI systems are built and evaluated
• Potential for ongoing work and contract extension as new projects launch