Senior Software Engineering Lead .net C#

Optum is a global organization that delivers care, aided by technology to help millions of people live healthier lives. The work you do with our team will directly improve health outcomes by connecting people with the care, pharmacy benefits, data and resources they need to feel their best. Here, you will find a culture guided by inclusion, talented peers, comprehensive benefits and career development opportunities. Come make an impact on the communities we serve as you help us advance health optimization on a global scale. Join us to start Caring. Connecting. Growing together.

We're looking for a Senior Software Engineer to join a team building a new, cloud-first healthcare payments platform using domain driven design. You'll work across a multi microservice ecosystem (applications and tooling), delivering features end-to-end - from domain modeling through API delivery, event publishing, infrastructure-as-code, and CI/CD.

This is a full-stack backend role with regular infrastructure involvement. You'll own features from aggregate design to production deployment.

Primary Responsibilities:

• Design and implement domain aggregates, value objects, and event-sourced workflows in C#/.NET
• Build RESTful APIs with versioned endpoints, RBAC authorization, and multi-tenant data isolation
• Write and maintain event contracts consumed by multiple services via Apache Kafka
• Author SQL migrations, Dapper queries, and repository implementations
• Write unit tests (xUnit, FluentAssertions, NSubstitute) and integration tests (Refit-based typed clients)
• Maintain Terraform modules for Azure infrastructure (AKS, Key Vault, Storage, Event Hubs)
• Contribute to shared CI/CD workflows (GitHub Actions) and Docker-based local development environments
• Coordinate cross-service changes when event schemas or API contracts evolve
• Comply with the terms and conditions of the employment contract, company policies and procedures, and any and all directives (such as, but not limited to, transfer and/or re-assignment to different work locations, change in teams and/or work shifts, policies in regards to flexibility of work benefits and/or work environment, alternative work arrangements, and other decisions that may arise due to the changing business environment). The Company may adopt, vary or rescind these policies and directives in its absolute discretion and without any limitation (implied or otherwise) on its ability to do so

Required Qualifications:

• 4+ years professional experience with C# and .NET (modern C# 12+ features: records, primary constructors, pattern matching, nullable reference types)
• ASP.NET Core Web API - controllers, routing, middleware, dependency injection
• Domain-Driven Design - aggregates, entities, value objects, domain events
• Event sourcing or CQRS patterns
• SQL Server - parameterized queries (Dapper), schema design, migrations
• Message-driven architectures - Kafka, Azure Event Hubs, or equivalent
• xUnit + mocking frameworks (NSubstitute or Moq) + fluent assertion libraries
• Docker and Docker Compose for local development
• Git - branching strategies, squash merge, conventional commit messages
• Understanding of RBAC/OAuth2 authorization and multi-tenancy patterns

Preferred Qualifications:

• Experience with code generation tooling (.NET CLI tools, Roslyn source generators)
• Terraform (HCL) - writing and maintaining infrastructure modules
• Azure cloud services - AKS, Key Vault, Storage Accounts, Front Door, App Gateway
• Kubernetes - deployments, ingress, network policies, autoscaling (KEDA)
• GitHub Actions - reusable workflows, composite actions
• Typed HTTP client design (Refit or similar)
• Polly resilience patterns (retry, circuit breaker, timeout)
• SonarQube quality gates and static analysis
• Healthcare payments domain knowledge (TIN, NPI, enrollments, provider onboarding)
• PCI-DSS data handling awareness
• OpenTelemetry / Datadog observability
• JFrog Artifactory for package and container management
• Venafi or similar certificate lifecycle management
• Java (Spring Boot) - enough to review or maintain event contract packages
• AI-assisted development workflows (GitHub Copilot, Codex)
• Elasticsearch for read-side search projections
• FluentValidation for request/command validation

What Success Looks Like

• Deliver features across multiple repositories without needing hand-holding on the project structure
• PRs are focused, well-titled (conventional commits), and include tests
• Comfortable touching main.tf when your feature needs a new secret, queue, or scaling config
• When you change an event contract, you know which downstream services to check
• Treat infrastructure and CI/CD as part of the feature, not someone else's problem

At UnitedHealth Group, our mission is to help people live healthier lives and make the health system work better for everyone. We believe everyone-of every race, gender, sexuality, age, location and income-deserves the opportunity to live their healthiest life. Today, however, there are still far too many barriers to good health which are disproportionately experienced by people of color, historically marginalized groups and those with lower incomes. We are committed to mitigating our impact on the environment and enabling and delivering equitable care that addresses health disparities and improves health outcomes - an enterprise priority reflected in our mission.