Senior Backend Engineer (C#) — AI Data Platform

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 Backend Engineer to build and optimize the data pipelines, annotation tooling, and evaluation systems that leading AI labs depend on to train and benchmark frontier models.

This is a fully remote, versátil contract role for an experienced engineer who wants to work on genuinely hard problems at the intersection of software engineering and AI research — without the constraints of a full-time role.

- 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# that power AI data pipelines and evaluation workflows

- Develop backend services and tooling for large-scale data annotation, validation, and quality control

- Build and maintain RESTful APIs and RPC services for reliable inter-service communication

- Integrate with cloud-native data services and orchestrate workflows across message bus architectures

- Improve reliability, performance, and safety across existing production C# codebases

- Collaborate with data, research, and engineering teams to support model training and evaluation workflows

- Identify bottlenecks and edge cases in system behavior and implement scalable, maintainable fixes





- Participate in synchronous design reviews to iterate on system architecture and implementation decisions

Who You Are

- 5+ years of professional experience building scalable backend services in C#

- Strong systems programming background with a deep understanding of performance and reliability trade-offs

- Mastery of modern frameworks for building RESTful APIs and RPC services

- Solid experience integrating with cloud-native data services and message bus architectures

- Native or fluent English speaker with clear written and verbal communication skills

- Self-directed and dependable — you can commit 20–40 hours per week and deliver without hand-holding

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

- Experience with distributed systems design or developer tooling

- Background in full-stack development alongside strong backend fundamentals

Why Join Us

- Work on real production systems used by leading AI research labs — this is high-impact engineering, not toy projects

- Fully remote and async-friendly — work when and where you do your best thinking

- Freelance autonomy with the structure of meaningful, ongoing technical work

- Collaborate with engineers and researchers at the cutting edge of AI development

- Potential for ongoing contract extension as projects scale and new work launches

📌 Senior Backend Engineer (C#) - AI Data Platform (México)
🏢 Alignerr
📍 México