Back-end Developer & Analyst

Back-end Developer & Analyst

Bull is a story. One with a century of European innovation and a working environment where experts design powerful, sustainable, and sovereign digital solutions, enabling states and industries to retain full control over their data and their AI. Bull is also thousands of engineers, researchers and passionate tech people shaping the future of high‑performance computing, AI, and quantum technologies. Every day, our teams push the boundaries of what is technologically possible – from next‑generation HPC architectures to exascale supercomputers – supported by world‑class R&D, more than 1,600 patents, and unique end‑to‑end capabilities spanning hardware design, software engineering, data science and quantum research. We are a people‑centric, innovation‑driven company, where collaboration spans Europe, the Americas and India. We share a common vision of a responsible and sustainable innovation that delivers concrete impact for our customers.

Bull is looking for a motivated and proactive Back‑end Developer & Analyst to join our international R&D team. In this role, you will take ownership of the implementation, integration, and testing of backend and security solutions, contributing to next‑generation cloud and HPC platforms. You will work in a dynamic, innovative environment, collaborating closely with technical and business stakeholders.

Key Responsibilities

• Design, develop, test, and maintain backend services using Kotlin / Java, microservices, and REST APIs.
• Participate in the full software development lifecycle within an Agile environment (Scrum).
• Contribute to analysis and definition of technical requirements, user stories, and solution design.
• Implement and integrate security and identity‑related solutions, including Proofs of Concept (PoCs).
• Work with CI/CD pipelines to support automated testing and deployment (Docker‑based environments).
• Collaborate with cross‑functional teams, including architects, DevOps, and product stakeholders.
• Ensure clean, maintainable, and well‑documented code following best practices.
• Support troubleshooting, performance optimization, and continuous improvement of backend systems.

Required Skills & Experience

• Bachelor's degree in Computer Science, Software Engineering, or a related technical field.
• 2+ years of professional experience in backend development using Kotlin and/or Java.
• Strong experience with microservices architecture, REST APIs, and Swagger/OpenAPI.
• Experience working in Agile/Scrum development environments.
• Solid experience with CI/CD tools and automated pipelines, including Docker.
• Good understanding of backend system integration and testing.
• Fluent English (written and spoken).

Other Desirable Skills

• Ability to quickly adapt to new frameworks, technologies, or programming languages.
• Experience with Kubernetes, including cluster lifecycle management, networking, security, and storage.
• Experience with Spring / Spring Boot and cryptographic libraries.
• Knowledge of Linux system administration and troubleshooting distributed systems.
• Experience with digital identity technologies, including Self‑Sovereign Identity, OIDC, OAuth 2.0, FIDO, and PKI certificates.
• Exposure to research and innovation projects (e.g. Horizon Europe / H2020 / FP7).

Personal Skills

• Proactive, autonomous, and solution‑oriented mindset.
• Strong analytical and problem‑solving skills.
• Team‑oriented attitude with good communication skills.
• Willingness to learn and grow in an innovative R&D environment.

Location: Madrid or Barcelona, or remote within Spain.

Benefits: Flexible work schedule half-day Fridays and an intensive summer workday supporting work life balance. Learning and Growth Opportunities to work with advanced technologies in an innovative and supportive R&D environment.