Fullstack Engineer (Portal)

Location: Barcelona, Barcelona, Spain

Department: Engineering

Prevent financial crime by building best-in-class SaaS solutions with our talented Hub teams in Barcelona! We’re looking for a Full-Stack Engineer who brings solid technical expertise, a product-driven mindset, and a collaborative spirit across diverse domains and skill levels. 

As a Full-stack engineer at Fourthline, you will: 

• Build and own user-facing features end-to-end, from frontend implementation to backend APIs. 
• Collaborate closely with Product and Design to translate requirements into high-quality, accessible, and maintainable user interfaces. 
• Develop and maintain frontend applications using Angular and TypeScript, with a focus on performance, usability, and scalability. 
• Design, develop, and evolve backend services within our .NET-based microservices architecture. 
• Ensure seamless integration between frontend and backend, including API design, versioning, and error handling. 
• Contribute to frontend (unit and end-to-end) and backend testing to ensure reliability and quality. 
• Participate in architectural discussions and contribute to engineering decisions within your team. 
• Take joint ownership of sprint goals, priorities, and delivery outcomes together with your teammates. 
• Work closely with Platform, QA, and other squads across the full development lifecycle. 
• Contribute to clear, pragmatic documentation and continuous improvement through knowledge sharing and learnings. 

Emphasis on Collaboration

At Fourthline, we foster a collaborative culture informed by industry knowledge (FinTech) and deep understanding of our business objectives. You will actively participate in chapter meetings, knowledge sharing sessions and cross-discipline alignments with other teams and engineering disciplines.  

Career Growth and Development

At Fourthline, we offer opportunities for learning and development, allowing you to work alongside and learn from experienced engineers. As you grow within our team, there are possibilities to grow to Senior Engineer and further (we have Staff Engineer level and beyond), with clear pathways to further your technical, problem solving and communication competencies, as well as build your knowledge of the FinTech industry. 

Our Stack

Angular, TypeScript, REST APIs, .NET 6–10, ASP.NET Web API, PostgreSQL, Marten (document & event store), Wolverine, RabbitMQ, Docker, Kubernetes (EKS), Terraform, AWS, and much more! 

Job Requirements 

• 3+ years of professional software development experience. 
• Experience working on production systems as a Full-stack or backend/frontend engineer. 
• Solid experience building web applications with TypeScript and a modern frontend framework (Angular preferred). 
• Understanding of frontend architecture, component design, and state management. 
• Experience integrating frontend applications with REST APIs. 
• Familiarity with frontend testing (unit and/or end-to-end). 
• Awareness of web security, accessibility, and performance best practices. 
• Proficiency in C# (.NET 6+ preferred). 
• Experience building REST APIs using ASP.NET Web API. 
• Familiarity with ORMs (EF Core) and LINQ. 
• Understanding of software design principles such as SOLID and common design patterns (DDD is a plus). 
• Experience with unit and integration testing (xUnit preferred; MSTest/NUnit are a plus). 
• Experience with Git and CI/CD pipelines (Azure DevOps preferred). 
• Exposure to cloud platforms such as AWS and/or Azure; experience with Kubernetes (EKS) and Terraform is a plus. 
• Ability to work on-site at our fantastic office in Barcelona at least 3 days a week as per our Hybrid Working Policy.  
• Language skills: English full professional proficiency.