Software Engineer (C#) - Internal Tooling

Alignerr; Seattle (WA); Remote; USD 83,000 - 124,000; Part time

Job summary

Alignerr is seeking a senior full-stack C# engineer for internal tooling and AI infrastructure. You will design and optimize high-performance C# systems, data pipelines, and evaluation workflows, collaborating with data, research, and engineering teams.

This is a remote hourly contract requiring 20-40 hours per week and strong production-grade C# experience. Ideal candidates have 3-5+ years of C# development, experience with cross-language integrations (Python interop), and a focus on

Qualifications

• 3-5+ years of professional experience writing production-grade C#.
• Native or fluent English speaker with strong written and verbal communication skills.
• Full-stack developer with a solid systems programming background.
• Experienced with interoperability scenarios - invoking Python ML models from .NET, wrapping native libraries, or similar cross-language integrations.
• Skilled at designing robust harnesses for benchmarking and evaluating system performance.
• Able to commit 20-40 hours per week with reliability and consistency.

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 existing 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, then implement scalable fixes
• Participate in synchronous design reviews to iterate on architecture and implementation decisions

Skills

C# development

Full-stack development

Systems programming

Cross-language integration

Performance benchmarking

English proficiency

Tools

Python interop with .NET

Wrapping native libraries

Job description

Software Engineer (C#) - Internal Tooling (AI Infrastructure)

About The Role

What if your C# skills could directly shape the infrastructure powering next-generation AI systems used by millions of people? We're looking for a senior full-stack C# engineer to build and optimize the internal tooling, data pipelines, and evaluation systems that leading AI labs depend on every day.

This is a fully remote contract role with flexible hours. You'll work 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

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 existing 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, then implement scalable 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
• Full-stack developer with a solid systems programming background
• 3-5+ years of professional experience writing production-grade C#
• Experienced with interoperability scenarios - invoking Python ML models from .NET, wrapping native libraries, or similar cross-language integrations
• Skilled at designing robust harnesses for benchmarking and evaluating system performance
• Able to commit 20-40 hours per week with reliability and consistency

Nice to Have

• Prior experience with data annotation, data quality, or evaluation systems
• Familiarity with AI/ML workflows, model training, or benchmarking pipelines
• Experience with distributed systems or developer tooling
• Background in research infrastructure or high-throughput data processing

Why Join Us

• Work on cutting-edge AI projects alongside leading research labs
• Fully remote and flexible - work when and where it suits you
• Freelance autonomy with the structure of meaningful, high-impact engineering work
• Make a direct, tangible contribution to the infrastructure driving the next generation of AI
• Potential for ongoing work and contract extension as new projects launch