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

$50-75/hrRemoteFreelanceCODING

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 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 working on real production systems — not toy projects. You'll be embedded in high-impact engineering workflows alongside data, research, and infrastructure teams pushing the frontier of AI development.

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

What You'll Do

  • Design, build, and optimize high-performance C# systems that power AI data pipelines and evaluation workflows
  • Develop full-stack tooling and backend services for large-scale data annotation, validation, and quality control
  • Improve reliability, performance, and safety across existing production C# codebases
  • Collaborate with data, research, and engineering teams to support model training and evaluation infrastructure
  • Identify bottlenecks and edge cases in data and system behavior — then implement scalable, production-ready 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
  • Experienced full-stack developer with a strong systems programming foundation
  • 3–5+ years of professional experience writing production C# code, with familiarity in modern standards and best practices
  • Strong background in performance optimization, concurrency (threading, atomics), and memory safety
  • Able to commit 20–40 hours per week consistently
  • Self-directed and comfortable working autonomously in a remote environment

Nice to Have

  • Prior experience with data annotation, data quality pipelines, or evaluation systems
  • Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
  • Experience with distributed systems or internal developer tooling
  • Exposure to C++17/C++20 or other systems-level languages

Why Join Us

  • Work directly with leading AI labs on production systems that shape next-generation models
  • Fully remote and flexible — structure your work around your life
  • Freelance autonomy with the depth and impact of meaningful, long-term technical work
  • Contribute to AI infrastructure that has real, lasting consequences for how models are built and evaluated
  • Potential for ongoing work and contract extension as new projects launch