Senior API designer

Senior API Designer / .NET 8 – Azure

Location: Barcelona

Experience: 5+ years in API Design

Language: Fluent English

✈️ Business travel: No

Environment: Azure, AWS, OpenShift | Agile

The Role

We are looking for a Senior API Designer / .NET Expert to join an international technology environment and play a key role in designing, governing and improving APIs at scale.

You will work at the intersection of business and technology, translating business requirements into robust API solutions while ensuring high standards around architecture, security, quality and maintainability.

You’ll also contribute to API governance and best practices across the wider technical community.

Your Responsibilities

• Design and specify APIs based on business and technical requirements.


• Review and challenge business requirements when needed to ensure scalable and efficient solutions.


• Ensure that API specifications are fully aligned with their real implementation.


• Create and review Pull Requests in Azure DevOps.


• Support technical and business stakeholders with API integration.


• Promote and evangelize API Design best practices across the organization.


• Contribute to internal API communities and the API Design Authority.


• Participate in improving team tools, processes and development practices.


• Conduct and share technology watch on API design, architecture and related technologies.


• Apply secure coding principles and ensure APIs follow appropriate quality and security standards.


• Contribute to production management, monitoring and automation practices.

️ Technical Environment

Must-have:

• Strong expertise in ASP.NET Core / C#


• .NET 8


• API Design – mandatory


• Minimum 5 years of experience in API Design


• Azure


• xUnit and automated testing


• Git – advanced usage


• PowerShell


• API security & secure coding practices


• DevOps, automation and scripting


• REST API design principles

Nice to have:

• OpenAPI 3.x / Swagger 2.0


• Swagger Editor / SwaggerHub


• Postman


• JSON, XML, YAML


• UML / sequence diagrams


• XMind / Mind Mapping


• Office 365


• RFC / ISO standards


• REST Richardson Maturity Model (Level 2/3)


• VS Code / Visual Studio

What We're Looking For

• Seniority and strong autonomy in API architecture and design


• Ability to communicate complex technical concepts clearly to both technical and business stakeholders


• Strong analytical and problem-solving skills


• Comfortable working in an Agile environment


• A proactive mindset and willingness to challenge existing solutions when appropriate


• Strong interest in technology trends and continuous improvement


• Fluent English

Why This Role?

This is more than a development role: you'll have a strategic impact on how APIs are designed, governed and integrated across the organization, while contributing to technical standards, communities and continuous improvement.