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

Alignerr Corp.; Seattle (WA); Remote; USD 83,000 - 138,000; Part time

Job summary

Alignerr is seeking a Senior C# Full-Stack Engineer to design and optimize data pipelines, annotation tooling, and evaluation systems for AI labs. This fully remote hourly contract role offers 20–40 hours per week and flexible hours, with collaboration across data, research, and engineering teams.

You should bring 3–5+ years of professional C# experience and a strong systems programming background, plus a focus on performance, concurrency, and memory safety.

Qualifications

• 3–5+ years of professional C# experience.
• Strong systems programming background.
• Experience building data pipelines, annotation tooling, and evaluation systems.

Responsibilities

• Design, build, and optimize high-performance C# systems for AI data pipelines and evaluation workflows.
• Develop full-stack tooling and backend services for data annotation, validation, and quality control at scale.
• Improve reliability, performance, and memory safety across existing C# codebases.

Skills

C#

Full-stack

Performance

Concurrency

Remote work

Job description

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 — working on real production systems with genuine, measurable impact.

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 — working on real production systems with genuine, measurable impact.

This is a fully remote contract role with flexible hours. If you're a sharp systems thinker who loves solving hard infrastructure problems, this is the kind of work that will actually push you.

• 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 large-scale AI data pipelines and evaluation workflows
• Develop full-stack tooling and backend services for data annotation, validation, and quality control at scale
• Improve reliability, performance, and safety across existing C# codebases — hunt down bottlenecks and ship scalable fixes
• Collaborate directly with data, research, and engineering teams to support model training and evaluation workflows
• Identify edge cases and systemic issues in data and system behavior and implement robust solutions
• Participate in synchronous design reviews to iterate on architecture and implementation decisions

Who You Are

• Full-stack developer with a strong systems programming background and 3–5+ years of professional C# experience
• Confident writing production-quality code with a focus on modern C# standards and best practices
• Deep understanding of performance optimization, concurrency (threading, atomics), and memory safety
• Clear, precise written and verbal communicator — you can articulate technical decisions without hand-waving
• Self-directed and reliable when working remotely with minimal supervision
• Native or fluent English speaker
• Able to commit 20–40 hours per week on a consistent basis

Nice to Have

• Prior experience with data annotation, data quality pipelines, or AI evaluation systems
• Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
• Experience with distributed systems or developer tooling
• Background working in fast-moving research or applied ML environments

Why Join Us

• Work directly with leading AI labs on cutting-edge production systems — not toy projects
• Fully remote and flexible — structure your work around your life
• Freelance autonomy with the focus and momentum of high-impact engineering work
• Collaborate with world-class data, research, and engineering teams pushing the frontier of AI
• Potential for ongoing work and contract extension as projects scale