Software Engineer – Database Kernel

In this role you work on Neo4j's kernel—building and improving the storage engine, transaction machinery, and core database features. You will optimize performance, ensure data integrity, and evolve the engine alongside a collaboration-focused team across Malmö and London. You’ll diagnose concurrency issues, shape architectural choices, and contribute to a high-assurance system that scales to billions of nodes and relationships. This is a hands-on, low-level engineering role in a renowned graph database company with a strong culture and impact-driven mission.

• Design, profile, and implement core database features, including storage formats, index structures, and recovery paths
• Diagnose concurrency bugs, race conditions, and lock contention
• Performance engineering: profile CPU, memory, off-heap memory, and disk I/O to reduce latency
• Review designs and PRs with emphasis on correctness and long-term maintainability
• Contribute to technical direction and architectural trade-offs as the engine evolves

• Systems programming experience near hardware
• Proficiency in Java; knowledge of C++, Rust, or Go and memory layouts
• Concurrency and data structures expertise: threads, locks, atomic operations, cache locality, algorithmic complexity
• Pragmatic engineering with thorough testing for kernel edge cases
• Collaborative, data-driven decision making and strong code review approach

• Collaborative
• Data-driven
• Open to feedback
• Java
• C++ / Rust / Go (knowledge transferable to Java-heavy codebase)
• Concurrency and synchronization