Senior Backend Engineer - Security Subsystem

Senior Backend Engineer - Security Subsystem Country: Spain Open Digital Services is the software development company of Santander Group powering the next generation of banks by creating innovative banking products and implementing them in collaboration with Santander Group Affiliates. Santander Group is one of the world's largest financial institutions and the Eurozone's leader, we're committed to being the best Digital Bank with Branches in the industry. Our mission at ODS is to design and support an advanced digital and omnichannel platform, ensuring the best customer experience using cutting-edge technology. Openbank, our flagship partner, is where we develop our most advanced concepts first. Be part of our Best-in-Class team and help us create unique value for our customers! THE DIFFERENCE YOU MAKE Open Digital Services is looking for a Backend Software Engineer based out of Madrid following a hybrid setting or remote within Spain. Build shared security services used by multiple products and markets, focusing on reliable APIs, state and session management, authentication and authorization flows, security controls, and the operational foundations that keep these services available and understandable. We’re shaping the way we work through innovation, cutting-edge technology, collaboration and the freedom to explore new ideas. To succeed in this role, you will be responsible for: Design, implement, test, deploy, and operate backend services and APIs used in security-critical customer journeys. Turn requirements into maintainable designs and incremental delivery plans with senior engineers and Team Leads. Write clear, well-tested code and improve automated testing, documentation, and developer workflows. Build observability into services and use logs, metrics, and traces to understand production behavior. Participate in sustainable on-call rotation, investigate incidents, and help remove root causes. Contribute to data modelling, caching, asynchronous processing, resilience, and performance improvements. Take part in code and design reviews and progressively own larger service areas and decisions. WHAT YOU’LL BRING Our people are our greatest strength. Every individual contributes unique perspectives that make us stronger as a team and as an organization. We’re enabling teams to go beyond by valuing who they are and empowering what they bring. The following requirements represent the knowledge, skills, and abilities essential for success in this role. Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions. Professional Experience +4 years of professional experience building backend applications or services in Go or Java (Required) Good understanding of APIs, data structures, databases, testing, version control, and basic distributed systems concepts. (Required) Experience debugging software in production or production-like environments. (Preferred) Language English (Required) Spanish (Preferred) Hard Skills APIs, data structures, databases, testing, and version control. (Required) Distributed systems concepts, caching, asynchronous processing, resilience, and performance. (Required) AWS, Redis, DynamoDB, PostgreSQL, or event-driven architecture. (Required ) ​ Soft Skills Strong analytical and problem-solving mindset. Clear communication and collaboration with engineers and stakeholders. Willingness to ask for help at the right time and learn unfamiliar systems. Quality mindset covering maintainability, edge cases, security, monitoring, and failure handling. READY TO TAKE THE NEXT STEP IN YOUR JOURNEY? Open Digital Services is an equal opportunity employer. All applicants will be considered as equal without paying attention to gender identity, sexual orientation, ethnicity, religion, age, political orientation, union membership nor disability status. We make recruiting decisions based on your experience and skills. We value your passion to discover, invent, simplify, and build. The personal data you provide as well as any data generated during the selection process are confidential and will be processed by Open Digital Services, S.L. with registered office at Plaza de Santa Bárbara 2, 28004 (Madrid), Madrid, Spain for the sole purpose of managing your participation in the selection processes and, where appropriate, to formalise your recruitment. For further information about your rights and data protection, please read the Open Digital Services Privacy Policy applicable to this type of data processing here