Senior .NET Engineer – 100% Remote (Spain Only) | UST
Location: Madrid, Spain (Remote only within Spain)
Company: UST
Position Type: Full-time
Experience Level: Senior
Work Mode: 100% Remote
Openings: 1
Schedule: Monday to Friday, 9:00 AM – 6:00 PM
Summer Hours: Intensive schedule in July & August
Job Code: CD-UST-DOTNET-SP25
Job Summary
UST, a U.S.-based global digital solutions leader certified as a Top Employer and Great Place To Work, is hiring a Senior .NET Engineer to join our remote team in Spain. If you're an experienced backend developer with a strong foundation in .NET Core, microservices, and cloud-native DevOps, this role is designed for you.
This opportunity includes flexible 100% remote work, a stable 9-to-6 schedule, and a summer-intensive schedule for improved work-life balance in July and August. Join a project in collaboration with a national leader in its sector.
Key Responsibilities
Design and lead microservices architecture using .NET Core 8+ with a focus on scalability, resilience, and DevOps practices.
Develop REST APIs using ASP.NET Core.
Implement resilience mechanisms with Polly (circuit breaker, retry, bulkhead) and HttpClientFactory.
Apply native dependency injection and centralized configuration strategies.
Write unit and integration tests using xUnit or NUnit and mocking with Moq/NSubstitute.
Follow clean architecture and domain-driven design (DDD) including bounded contexts and aggregates.
Work with microservice patterns: API Gateway (YARP/Ocelot), service registry (Steeltoe Discovery, Consul), CQRS/Event Sourcing.
Use Docker for multi-stage builds and deploy with Kubernetes (AKS/EKS/GKE) using Helm, Kustomize, and Redis.
Secure APIs using OAuth2, OIDC, JWT with Azure AD, Duende IdentityServer, Auth0, and Keycloak.
Ensure observability with OpenTelemetry, Prometheus, Grafana, Jaeger, Zipkin, and logging using Serilog.
Maintain code quality using SonarQube/SonarCloud, Roslyn analyzers, Coverlet.
Use Git (GitFlow/trunk-based) and CI/CD pipelines with Azure DevOps.
Required Skills & Qualifications
Proven experience with backend development using .NET Core (v8 or above).
Strong understanding of REST API design and ASP.NET Core.
Familiarity with microservices architecture and clean/hexagonal design.
Experience with Docker, Kubernetes, and Helm.
Hands-on with DevOps tools like Azure DevOps and Git.
Knowledge of testing frameworks (xUnit/NUnit) and mocking libraries (Moq, NSubstitute).
Familiarity with OAuth2, OIDC, JWT, and secure API practices.
Experience with observability and monitoring tools (Serilog, Prometheus, Grafana).
Fluent in English; ability to collaborate in a remote Agile team.
Benefits
23 working days of vacation per year, plus December 24 & 31 off.
Private health insurance, life & accident insurance, and remote work assistance.
Flexible compensation plans (meal card, childcare vouchers, transport card, family medical insurance, English classes).
Free access to top e-learning platforms.
Professional stability and internal career path programs.
Employee referral bonus scheme.
Salary distribution option: 12 or 14 payments.
Strong work-life balance with psychological, nutritional, and fitness consultations.
Discounts via UST Club and access to partner gyms.
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About UST
UST is a U.S.-based multinational digital technology company with over 35,000 employees across 35+ countries, known for its culture of innovation and commitment to diversity and inclusion. We deliver powerful digital transformation solutions to the world’s top enterprises.
