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, adaptable 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.
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 commi