Senior Backend Developer / Full Stack / Frontend Developers

At Fourthline, our mission is to fight financial crime. We help protect the global financial system by verifying millions of identities for banks, neobanks, online brokers, crypto exchanges, and insurers like N26, Trade Republic, flatexDEGIRO, Nationale Nederlanden, Qonto, Shine, Solarisbank, and more.

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.

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.

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!

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).
• NET Web API.
• 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.
• English full professional proficiency.