Senior Backend Engineer (C#) - AI Data Platform

Alignerr Corp.; Brasil; Remote; BRL 96,000 - 152,000; Full time

Job summary

Alignerr is seeking a Senior Backend Engineer (C#) to design and build data pipelines, annotation tooling, and evaluation systems powering AI labs. This fully remote, flexible hourly contract role requires 20–40 hours per week and a track record of scalable backend systems.

You will develop backend services and tooling for large-scale data annotation, validation, and quality control, collaborating with data, research, and engineering teams to support model training and evaluation.

Qualifications

• 5+ years of professional experience building scalable backend services in C#.
• Strong systems programming background with full-stack development experience.
• Experience with RESTful APIs and RPC services.
• Experience integrating with cloud-native data services and orchestrating workflows via message bus architectures.

Responsibilities

• Design, build, and optimize high-performance systems in C# that support AI data pipelines and evaluation workflows.
• Develop backend services and full-stack tooling for large-scale data annotation, validation, and quality control.
• Improve reliability, performance, and safety across existing C# codebases used in production AI systems.
• 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, and implement scalable, robust fixes.
• Participate in synchronous design reviews to iterate on system architecture and implementation decisions.

Skills

C# backend engineering

RESTful APIs

RPC services

Cloud-native data services

Message bus architectures

Job description

Senior Backend Engineer (C#) — AI Data Platform

What if your C# engineering skills could directly shape the infrastructure powering the world's most advanced AI systems? We're looking for a Senior Backend Engineer to design and build 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 thrives on high-impact, technically demanding work. If you've spent years building scalable backend systems and want to apply that expertise at the frontier of AI development — this is the role.

• Organization: Alignerr
• Type: Hourly Contract
• Location: Remote
• Commitment: 20–40 hours/week

What You'll Do

• Design, build, and optimize high-performance systems in C# that support AI data pipelines and evaluation workflows
• Develop backend services and full-stack tooling for large-scale data annotation, validation, and quality control
• Improve reliability, performance, and safety across existing C# codebases used in production AI systems
• 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, and implement scalable, robust fixes
• Participate in synchronous design reviews to iterate on system architecture and implementation decisions

Who You Are

• Native or fluent English speaker with clear written and verbal communication skills
• 5+ years of professional experience building scalable backend services in C#
• Strong systems programming background with full-stack development experience
• Deep familiarity with modern frameworks for building RESTful APIs and RPC services for inter-service communication
• Experienced integrating with cloud-native data services and orchestrating workflows via message bus architectures
• Able to commit 20–40 hours per week with consistency and reliability

Nice to Have

• Prior experience with data annotation, data quality systems, or evaluation pipelines
• Familiarity with AI/ML workflows, model training, or benchmarking infrastructure
• Experience with distributed systems or internal developer tooling
• Background working with or alongside AI research teams

Why Join Us

• Work on real, production-grade systems used by leading AI research labs
• Fully remote and flexible — work on your own schedule from anywhere
• Freelance autonomy with the structure of meaningful, high-impact engineering work
• Contribute directly to the infrastructure that shapes how next-generation AI models are built and evaluated
• Potential for ongoing work and contract extension as new projects launch