Senior Backend Engineer (C#) - AI Data Platform

Alignerr Corp.; Seattle (WA); Remote; USD 96,000 - 165,000; Part time

Job summary

Alignerr is seeking a Senior Backend Engineer (C#) to design and build data pipelines, annotation tooling, and evaluation infrastructure powering AI labs. This fully remote, hourly contract role offers 20–40 hours per week and the chance to work on production AI systems.

You will design high-performance C# systems, develop backend services for data annotation and validation, and collaborate with cross-functional teams to ensure scalable, reliable infrastructure for model training and evaluation.

Qualifications

• 5+ years of professional experience building scalable backend services in C#.
• Strong experience with RESTful APIs and RPC services.
• Experience with cloud-native data services and message bus architectures.
• Deep systems programming background.

Responsibilities

• Design, build, and optimize high-performance C# systems supporting AI data pipelines and model evaluation workflows.
• Develop backend services and tooling 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 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.

Skills

5+ years in C# backend

RESTful APIs

RPC services

Cloud-native data services

Message bus architectures

Systems programming

Job description

Senior Backend Engineer (C#) — AI Data Platform

What if your C# engineering skills could directly shape the infrastructure powering the world’s most advanced AI systems? We're looking for a Senior C# Engineer to design and build the data pipelines, annotation tooling, and evaluation infrastructure that leading AI labs depend on to train and improve next-generation models.

About The Role

What if your C# engineering skills could directly shape the infrastructure powering the world’s most advanced AI systems? We're looking for a Senior C# Engineer to design and build the data pipelines, annotation tooling, and evaluation infrastructure that leading AI labs depend on to train and improve next-generation models.

This is a fully remote, flexible contract role working on real production systems at the frontier of AI development. If you're a seasoned backend engineer who wants meaningful, high-impact work — this is it.

• 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 model evaluation workflows
• Develop backend services and tooling 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 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
• 5+ years of professional experience building scalable backend services in C#
• Strong systems programming background with full-stack development experience
• Deep expertise in modern frameworks for RESTful APIs and RPC services
• Experienced integrating cloud-native data services and orchestrating workflows via message bus architectures
• Able to commit 20–40 hours per week with reliability and consistency

Nice to Have

• Prior experience with data annotation, data quality pipelines, or model evaluation systems
• Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
• Background in distributed systems design or developer tooling

Why Join Us

• Work directly on cutting-edge AI projects alongside the world's leading research labs
• Fully remote and flexible — structure your hours around your life
• Freelance autonomy with the substance of high-impact, technically challenging work
• Contribute to infrastructure that shapes the future of AI at a foundational level
• Potential for ongoing engagement and expanded scope as new projects launch