Senior .NET API Engineer

freeC's Client

Client Description

The client operates in the insurance and financial services domain, delivering projects related to large-scale data processing and integration of partner systems. The organization is undergoing a technology transformation focused on modernizing an existing .NET-based data processing environment into a modern, scalable, cloud-based data architecture. A key element of the ecosystem consists of transactional systems, integration platforms, and Microsoft Fabric-based data services that communicate through extensive APIs.

Role Description

We are looking for a Senior .NET API Developer to join a team responsible for the development and maintenance of the integration layer, API endpoints, orchestration services, and supporting platform components enabling the new data ecosystem. The role combines software engineering, integration development, and platform modernization activities, including the migration and retirement of legacy solutions. The engineer will work closely with integration architects, data engineers, and analysts to deliver secure, scalable, and maintainable solutions aligned with engineering standards.

Responsibilities

• Design, development, and maintenance of REST APIs and integration services in .NET
• Building orchestration services and automation components supporting the ETL and data platform ecosystem
• Implementation of endpoints used to integrate the data platform with upstream and downstream systems
• Development of services supporting ingestion, enrichment, routing, and outbound integrations
• Development of reusable integration components accelerating partner onboarding and data processing
• Integration with enterprise platforms, including authentication, token management, and API consumption components
• Collaboration on migrating processes from a legacy .NET environment and supporting legacy platform decommissioning activities
• Refactoring or replacement of existing services as part of platform modernization initiatives
• Ensuring code quality, security, resilience, testability, performance, and maintainability
• Applying modern engineering practices including TDD, code reviews, and automated testing
• Working with CI/CD pipelines and deployment automation
• Working in the team in an agile delivery model (backlog management, planning, reviews)
• Producing technical documentation and operational runbooks
• Participation in solution design and proposing technical improvements
• Supporting Build-Operate-Transfer activities and mentoring less experienced engineers where required
• Working in an environment supported by AI-assisted development (automation, code reviews, boilerplate generation)
• Validating and governing AI-generated outputs to ensure quality and compliance

Technical Requirements

• Total 8-10 years of experience with Minimum 5 years of experience as a .NET Developer
• Very good knowledge of C# and .NET / .NET Core
• Extensive experience in designing and implementing RESTful APIs
• Strong knowledge of integration patterns and enterprise system integrations
• Experience building secure, scalable, and maintainable distributed systems
• Practical experience with Azure services and cloud-native architectures
• Experience working with databases (SQL)
• Knowledge of API performance, security, scalability, and resilience concepts
• Strong understanding of DevOps practices, CI/CD pipelines, and deployment automation
• Experience with automated testing and code review practices
• Experience working with Git
• English at a minimum B2+ level – international working environment
• Azure integrations (APIs, Service Bus, authentication)
• ADF and Azure Functions
• Understanding of OneLake
• Ability to navigate and debug solutions built on Microsoft Fabric/ or similar 

Nice to Have

• Experience in data processing, ETL, or data integration projects
• Exposure to Microsoft Fabric ecosystem
• Knowledge of microservices-based architectures
• Experience collaborating with data engineering teams
• Experience with Azure Functions
• Experience with event-driven architectures
• Insurance or financial services domain experience
• Experience working in Build-Operate-Transfer (BOT) delivery models
• Openness to working with AI-supported tools in the software development lifecycle
• Experience with AI-assisted software development
• English proficiency required: minimum B2+

• Full-remote working (UK timezone)
• Open for 2nd job if you can arrange your time
• NET salary (PIT will be covered by the company)
• Contract: 6 months & possibly extend