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 to design and build high-performance C# data pipelines, annotation tooling, and evaluation systems for AI workloads. This is a fully remote hourly contract, with flexible hours and 20–40 hours per week.

You will work with data, research, and engineering teams on production systems at the frontier of AI, shipping reliable APIs and scalable backends to support model training and evaluation.

Qualifications

• 5+ years of professional experience building scalable backend services in C#.
• Strong experience with RESTful APIs and RPC-based inter-service communication.
• Experience with cloud-native data services and message bus architectures.

Responsibilities

• Design, build, and optimize high-performance backend systems in C# supporting large-scale AI data pipelines and evaluation workflows.
• Develop backend services and tooling for data annotation, validation, and quality control at scale.
• Build and maintain RESTful APIs and RPC services for reliable inter-service communication.
• Integrate with cloud-native data services and orchestrate workflows via message bus architectures.
• Identify bottlenecks, edge cases, and reliability issues across existing codebases — then implement scalable fixes.
• Collaborate with research and engineering teams to support model training, benchmarking, and evaluation workflows.
• Participate in synchronous design reviews and iterate on system architecture decisions.

Skills

C# backend

RESTful APIs

RPC inter-service

Cloud-native data

Performance optimization

English communication

Tools

Message bus architectures

Cloud services

Job description

Senior Backend Engineer (C#) — AI Data Platform

What if your C# expertise could directly shape the infrastructure powering the next generation of AI? We're looking for a Senior Backend Engineer to design and build the high-performance data pipelines, annotation tooling, and evaluation systems that leading AI labs depend on to train and improve their models. This is a fully remote contract role with flexible hours. You'll be working 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 backend systems in C# supporting large-scale AI data pipelines and evaluation workflows
• Develop backend services and tooling for data annotation, validation, and quality control at scale
• Build and maintain RESTful APIs and RPC services for reliable inter-service communication
• Integrate with cloud-native data services and orchestrate workflows via message bus architectures
• Identify bottlenecks, edge cases, and reliability issues across existing codebases — then implement scalable fixes
• Collaborate with research and engineering teams to support model training, benchmarking, and evaluation workflows
• Participate in synchronous design reviews and iterate on system architecture decisions

Who You Are

• 5+ years of professional experience building scalable backend services in C#
• Deep command of modern C# frameworks for RESTful APIs and RPC-based inter-service communication
• Experienced integrating with cloud-native data services and message bus architectures
• Systems-level thinker who can identify performance issues and architect clean, scalable solutions
• Clear, concise written and verbal communicator — comfortable working with cross-functional teams
• Native or fluent English speaker
• Able to commit 20–40 hours per week consistently

Nice to Have

• Prior experience with data annotation platforms, data quality systems, or evaluation pipelines
• Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
• Experience with distributed systems design or developer tooling
• Full-stack background with frontend exposure alongside a strong backend foundation

Why Join Us

• Work directly on cutting-edge AI projects alongside leading research labs
• Fully remote and flexible — work from wherever you do your best work
• Freelance autonomy with the structure of meaningful, high-impact engineering work
• Contribute to infrastructure that shapes how next-generation AI systems are built and evaluated
• Potential for ongoing work and contract extension as new projects launch