Senior Backend Software Engineer
Confirmed on the employer's own hiring board on Oct 16, 2026. First seen by Alion on Feb 11, 2026. Fourthline scores B on the Alion truth index.
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.
Having started our journey in January 2018, we're incredibly proud to count around 250 employees between our Amsterdam and Barcelona offices with over 50 nationalities.
Prevent financial crime by building best-in-class SaaS solutions with our talented Anti-Money Laundering (AML) and Bank Account Verification (BAV) + Qualified Electronic Signatures (QES) teams in Barcelona -we’re looking for a Senior Backend Software Engineer who brings solid technical expertise, a product-driven mindset, and a collaborative spirit across diverse domains and skill levels.
As a senior backend engineer at Fourthline, you will:
- Design, develop, maintain, and improve our microservices, and take responsibility for thorough testing and reliable deployments of your stories.
- Professionally manage your tasks, priorities and deliverables, taking joint ownership with your teammates for the sprint goals.
- Utilize your experience to contribute to our growth through lessons learned from your successes and failures.
- Take responsibility for engineering excellence and participate in architectural decision-making within your team.
- Contribute to thorough documentation-crucial for ensuring success and minimizing questions!
- Understand the entire development lifecycle and work closely with other members in squads, including Platform and QA teams.
- Employ both technical and soft skills to address challenges, recognizing that solutions often require a blend of technology-based and people-based strategies.
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 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
.NET 5-8 - Our cloud-based microservices architecture includes REST APIs, Docker, Message Queues (RabbitMQ), RDBMS (PostgreSQL), Wolverine, Marten (Doc + Event stores), and much more!
Job Requirements
- Minimum 5 years software development experience in one or more general-purpose programming languages.
- Good knowledge of .NET 5-8, or .NET Core 3.x
- Proficiency in C# (version 10 or later).
- Experience in unit and integration testing with XUnit (MSTest/NUnit are a plus).
- Familiarity with ORMs (EF Core) and knowledge of Linq.
- Experience implementing REST APIs using .NET Web API.
- Understanding of SOLID principles and Domain-Driven Design (DDD).
- Knowledge of common software design patterns.
- Experience with Git and CI/CD in Azure DevOps.
- Experience with cloud providers such as AWS and Azure; experience with EKS and Terraform is highly valued.
- 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.
At Fourthline, we believe diversity enriches our culture and inspires you to do your best work. We value your unique talents and perspectives, welcoming them into a safe and inclusive working environment, to ultimately deliver the best products to our customers and society. You're welcome here. Fourthline is for everyone.
Our hiring process is designed to be equal, fair, and transparent. We welcome people from all backgrounds, ethnicities, genders, sexual orientations, ages, abilities, religions, and experiences in life. If you're excited about this role, but your experience does not align perfectly with every qualification in the job description, we encourage you to apply anyways. You may just be the right candidate for this or other roles.