Senior C# Full-Stack Engineer — AI Data & Infrastructure
Role summary
Alignerr is seeking a Senior C# Full-Stack Engineer for a fully remote, flexible contract role. The engineer will build and optimize data pipelines, annotation tooling, and evaluation systems for AI models. Responsibilities include designing and building high-performance C# systems, developing full-stack tooling, improving system reliability and performance, and collaborating with data, research, and engineering teams. Requires 3-5+ years of production C# experience, strong systems programming background, and knowledge of performance optimization, concurrency, and memory safety. Prior experience with data annotation platforms, AI/ML workflows, or distributed systems is preferred.
About The Role
What if your C# expertise could directly shape the infrastructure powering the world's most advanced AI systems? 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 next-generation models.
This is a fully remote, flexible contract role for an experienced engineer who wants to work on real production systems at the frontier of AI — not just maintain legacy code, but architect meaningful infrastructure that matters.
- Organization: Alignerr
- Type: Hourly Contract
- Location: Remote
- Commitment: 20–40 hours/week
What You'll Do
- Design, build, and optimize high-performance C# systems that support 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 used in production AI environments
- Collaborate closely 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, robust fixes
- 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 deep command of C#
- 3–5+ years of professional experience writing production-grade C# code, with familiarity with modern standards
- Solid grounding in performance optimization, concurrency (threading, atomics), and memory safety
- Native or fluent English speaker with clear written and verbal communication skills
- Self-directed and reliable — able to commit 20–40 hours per week and deliver consistently without hand-holding
- Comfortable navigating complex codebases and making principled architectural decisions under real constraints
Nice to Have
- Prior experience with data annotation platforms, data quality systems, or evaluation infrastructure
- Familiarity with AI/ML workflows, model training pipelines, or benchmarking systems
- Experience building distributed systems or developer tooling at scale
- Background working alongside research or applied AI teams
Why Join Us
- Work at the frontier of AI — your code will directly influence how the world's leading models are built and evaluated
- Fully remote and flexible — structure your hours around your life, not the other way around
- Collaborate with world-class research and engineering teams on genuinely hard problems
- Freelance autonomy with the substance of high-impact, technically demanding work
- Potential for ongoing work and contract extension as projects evolve and expand