API Developer – .NET

Your mission

Role purpose

A hands-on API developer specializing in .NET API design and delivery within the organization. You will own the implementation of robust, secure, and scalable APIs, advocate API-first practices, and collaborate with Product, Architecture, Security, and Platform teams.

Primary Focus

• API design, development, and lifecycle for .NET-based products
• API-first approach: REST, gRPC, OpenAPI/Swagger, contract testing, versioning
• Cloud-native integrations, DevOps, CI/CD, and observability
• Collaboration with Digital Product Owner (DPO), Enterprise Architecture, Security, and Platform teams
• Balance speedy delivery with long-term maintainability and regulatory awareness as a plus
• Your profile

Key Responsibilities

• Own the technical direction and architecture for the API surface in your domain
• Design and evolve API architectures; define contracts, versioning, security, and observability
• Translate product features into technical designs and actionable work
• Develop, test, and document APIs; implement contract tests and robust integration tests
• Lead code reviews and ensure consistent coding standards and quality
• Establish and maintain DevOps practices, CI/CD pipelines, automated tests, and monitoring
• Collaborate with Platform, Security, and Enterprise Architecture teams
• Identify, communicate, and mitigate technical risks, dependencies, and debt
• Support incident resolution and root cause analysis
• Ensure alignment with non-functional requirements (performance, reliability, maintainability, security)
• Align with regulatory/compliance requirements where relevant (treated as a plus)

Required Qualifications

• Strong hands-on experience as a .NET API developer or senior engineer
• Expertise in C#, .NET (Core/5/6/7+) and the modern .NET ecosystem
• Deep experience designing, building, and consuming APIs (REST and/or gRPC)
• Proficiency with API tooling and practices: OpenAPI/Swagger, contract testing, API gateways, security best practices
• Solid understanding of cloud-native architectures and integrations; experience with Azure or AWS
• Proficient in DevOps, CI/CD, automated testing (unit, integration, contract), and observability/monitoring
• Strong collaboration and communication skills; effective with DPO/EA/security teams
• Awareness of security, privacy, and audit considerations in API data

Nice-to-Have

• Experience with interoperability standards or cross-domain integration
• Regulatory/compliance domain experience is a plus but not required
• Containerization and orchestration (Docker, Kubernetes)
• Advanced observability tools and APM solutions

Skills and Competencies

Technical execution

delivers robust APIs with high code quality and maintainability

API craftsmanship

strong focus on contracts, versioning, security, and observability

Decision making

clear technical choices with well-communicated trade-offs

Collaboration

works effectively with Product, Architecture, Security, and Platform teams

Quality focus

integrates security, privacy, and regulatory considerations into design and delivery

Collaboration and Stakeholders

• Digital Product Owner (primary counterpart)
• Domain engineers and developers within the API team

Enterprise Architect

• Platform teams (Cloud, Integrations, Analytics)
• Security, infrastructure, and operations teams
• External vendors and implementation partners

Decision Authority

• Technical design and implementation choices within the API domain
• Day-to-day technical prioritization and team execution
• Technical risk mitigation, debt management, and release readiness
• Engineering practices, tooling, and development workflows within agreed standards

Location and Working Model

Valencia, Spain

Hybrid / remote-friendly depending on policy and team needs

Background & Experience

• Strong background as a senior engineer or API specialist
• Experience delivering API-centric products in agile teams
• Proficient with cloud platforms, modern architectures, and DevOps practices
• Ability to collaborate with Enterprise Architecture on standards
• Experience in enterprise-scale or regulated environments is a plus
• What we offer

Medical insurance

Your health, and your family's, is our top priority. You're fully covered.

Holiday flat in Valencia

Dreaming of sunny days in Spain? Our company flat is ready for your next getaway.

Gifts for special occasions

We love celebrating you. Expect thoughtful surprises on Easter, Women's Day, Father's Day, and more.

Anniversary gifts

Your 1st, 5th, and 10th work anniversaries are milestones worth celebrating, and we mark each of them with a special gift.

Team-building events

We value connection beyond work, offering engaging team experiences in great locations to inspire collaboration and fun.

End of year celebrations

We wrap up each year with a special celebration, filled with joy, laughter, and unforgettable moments.

Day off on your birthday

Your special day is yours to enjoy, no work required.

Community and social initiatives

We bring people together through activities like Bring Your Kids to the Office Day, donation drives, tree planting, sporting events, decorating the Christmas tree with your colleagues, celebrating new office openings, Principal33's anniversary, and more.

Access to Udemy

Growth matters, so you get unlimited access to thousands of courses. Develop your skills anytime, anywhere.

German language courses

Dedicated courses to help you build your German skills, supporting both personal and professional growth.

Personal and professional growth

We support your development through masterclasses with experienced trainers, and we're open to investing in courses and training that help you grow.