Back End Developer

Hybrid role: 3 days per week at the office in Valencia (Spain)At Principal33 we strive to make happiness at work a reality. Because it's not just about the money, it's also about the work environment and appreciation. It's about creating the best team setup you can imagine and getting involved in the things you're passionate about. And you can be a part of it, because it's fun to get things doneWe want our employees to innovate and we allow them to do what they are truly passionate about. Based on this conviction, Principal33 aligns its strategy around its vision: to become a leading IT service company and a better working-life balance. With currently around 200 employees from different countries, we are actively shaping the future of work.As a Backend Developer you will play a key role in building robust, scalable systems that support AI-driven products operating in real time. We are looking for someone who combines strong technical expertise with ownership, system-level thinking, and collaboration.You will work on an AI-powered video analytics platform focused on real-time detection and alerting. The platform processes live video streams and generates alerts when predefined events occur. Your work will ensure that the backend systems are secure, reliable, and ready to scale as the platform grows.Key ResponsibilitiesDesign, develop, and maintain backend services in C# (.NET Core) for the SaaS platformDesign and manage database schemas and data access layers using Entity Framework Core, ensuring performance and data integrityBuild and maintain secure, well-documented REST APIs consumed by frontend and other servicesImplement backend business logic using DDD and Clean Architecture principles, ensuring clean separation of concernsDesign and operate microservice-based and event-driven systems, including inter-service communication via Apache KafkaImplement authentication and authorization (RBAC) using ORY Kratos & ORY Keto, ensuring secure access controlSupport real-time system behavior and live updates using SignalR where applicableCollaborate with frontend, AI, and platform teams to design and integrate end-to-end featuresEnsure backend systems meet high standards of scalability, reliability, security, and observabilityWrite and maintain unit and integration tests to ensure system stability and correctnessParticipate in architectural decisions and contribute to the long-term evolution of the backend platformRequirementsMust-Have QualificationsStrong professional experience as a Backend Developer working with C# and .NET CoreProven experience in database design and data access using Entity Framework Core or equivalent ORMsHands-on experience building secure REST APIs for production systemsSolid understanding and practical application of DDD and Clean Architecture in backend developmentExperience implementing authentication and authorization, including role-based access control (RBAC)Familiarity with ORY Kratos and ORY Keto, or similar identity and authorization systemsExperience working with microservices and inter-service communication, including Apache KafkaExposure to real-time systems and technologies such as SignalRStrong experience writing and maintaining unit and integration testsAbility to collaborate effectively with cross-functional teams and communicate technical concepts clearlyNice-to-HaveExperience working in event-driven architectures and distributed systemsExposure to Python services within a heterogeneous backend ecosystem (REST APIs, Kafka-based communication)Experience supporting AI-driven, data-intensive, or video analytics platformsBackground in SaaS products operating in high-availability or mission-critical environmentsWhat we offerBenefitsFlexible work hoursPrivate medical insuranceDay off on your birthdayReferral bonus if you bring your contactsGifts for special occasionsOffice that takes care of your well-being and on top of all we are pet friendly, bring your pet to the officeFridge full of snacks at the office, healthy ones and not so healthy as wellInternational and multicultural environment(Self)-DevelopmentContinuous training, we will help you improve your technical skills, evolve in the tech community and develop as a professional.We are an active part of the tech-community. You may have the opportunity to attend and participate in local and international tech-events.Wanna join?