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

Alignerr; United States; Remote; GBP 83,000 - 165,000; Part time

Job summary

Alignerr is seeking a Senior C# Full-Stack Engineer to design and optimize data pipelines, annotation tooling, and evaluation systems used by leading AI labs. This fully remote hourly contract offers 20–40 hours per week, flexible hours, and the chance to work at the frontier of AI development.

You will build high-performance C# systems, collaborate with research and engineering teams, and tackle production-readiness challenges with a focus on reliability and memory safety.

Qualifications

• Native or fluent English speaker with strong written and verbal communication skills.
• Experienced full-stack developer with a solid systems programming foundation.
• 3–5+ years of professional experience writing production C# (modern standards preferred).
• Deep understanding of performance optimization, concurrency (threading, atomics), and memory safety.
• Methodical problem-solver who thrives in fast-moving, high-stakes technical environments.
• Able to commit 20–40 hours per week with reliability and professionalism.

Responsibilities

• Design, build, and optimize high-performance C# systems supporting 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 production C# codebases.
• Collaborate with data, research, and engineering teams to support model training and evaluation workflows.
• Identify bottlenecks and edge cases in data and system behavior, and implement scalable, production-ready fixes.
• Participate in synchronous design reviews to iterate on architecture and implementation decisions.

Skills

C#

Full-stack development

Performance optimization

Concurrency

Memory safety

English communication

Job description

About The Role

What if your C# expertise could directly shape the infrastructure powering the next generation of AI models? 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 to train and improve their most advanced models.

About The Role

What if your C# expertise could directly shape the infrastructure powering the next generation of AI models? 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 to train and improve their most advanced models.

This is a fully remote contract role with meaningful technical challenges, flexible hours, and the chance to work at the frontier of AI development — without leaving your home office.

• 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 full-stack tooling and backend services for large-scale data annotation, validation, and quality control
• Improve reliability, performance, and safety across production C# codebases
• Collaborate with data, research, and engineering teams to support model training and evaluation workflows
• Identify bottlenecks and edge cases in data and system behavior, and 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 strong written and verbal communication skills
• Experienced full-stack developer with a solid systems programming foundation
• 3–5+ years of professional experience writing production C# (modern standards preferred)
• Deep understanding of performance optimization, concurrency (threading, atomics), and memory safety
• Methodical problem-solver who thrives in fast-moving, high-stakes technical environments
• Able to commit 20–40 hours per week with reliability and professionalism

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
• Background working alongside research or data science teams

Why Join Us

• Work directly with leading AI research labs on real production systems — not toy projects
• Fully remote and flexible — structure your work around your life
• Freelance autonomy with the depth and continuity of meaningful, long-term technical work
• Make a direct, tangible impact on the AI systems shaping how the world uses technology
• Potential for ongoing work and contract extension as new projects launch