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