Senior Software Engineer | Database Optimization

Location: European Union About CAST AI CAST AI is an automation platform that optimises cloud and AI infrastructure at scale. By embedding autonomous decision-making directly into Kubernetes and cloud environments, CAST AI continuously improves performance, reliability and efficiency in production. More than 2,100 companies already rely on CAST AI, including Akamai, BMW, Cisco, FICO, Hugging Face, NielsenIQ, Swisscom and TGS. CAST AI operates across 34 countries and has a remote-first culture built around small, highly technical teams. In January 2026, the company achieved unicorn status following a strategic investment from Pacific Alliance Ventures, bringing its valuation above $1 billion. About the role Databases are still managed manually. Engineers monitor slow queries, decide which indexes to add, tune connection limits and introduce caching, often without being able to prove whether those changes will improve performance in production. CAST AI is building an autonomous database administrator that can identify problems, recommend improvements and validate that those improvements work before customers rely on them. As a Senior Software Engineer on the Database Optimisation team, you will work across two core components: Database Gateway: A high-performance Rust proxy that sits in front of customer databases and provides capabilities such as rate limiting and caching without requiring application changes. Database Agent: A Go-based service that analyses database workloads and produces recommendations such as index suggestions and query improvements. The focus is not simply producing recommendations. Every recommendation needs to be reliable and validated. A stale read, incorrect cache decision or poor index suggestion can affect a customer’s production system, so correctness is central to the role. You will help shape the architecture, technical direction and roadmap of the autonomous DBA product. What you will do - Design, build and operate the Database Gateway. - Develop high-performance services in Go and Rust. - Work on database caching, rate limiting and other gateway capabilities. - Build the Database Agent’s recommendation engine. - Develop systems for index suggestions, query analysis and query improvements. - Work on cache invalidation and data consistency, where correctness is critical. - Create methods for safely validating database recommendations before they are applied. - Debug complex production issues across the gateway, agent and underlying database systems. - Analyse database performance, query behaviour and workload patterns. - Collaborate with product and engineering teams on problems without established solutions. - Contribute to product direction, technical decisions and the engineering roadmap. - Help shape the next generation of automated database administration. What we are looking for - Strong software engineering fundamentals, including clean abstractions and maintainable code. - Professional experience building production services in Go. - In-depth knowledge of PostgreSQL or MySQL. - Understanding of how database clients, drivers and wire protocols work. - Strong debugging, optimisation and performance-tuning skills. - Experience with query profiling, index design and database tuning beyond ORM usage. - Experience taking a complex technical project from design through to production. - Strong written and spoken English. - A proactive and adaptable approach to working in a fast-moving environment. - Comfort working with ambiguity and contributing to technical direction. Nice to have - Rust experience, particularly with high-performance network services or proxies. - Experience building or extending database proxies, gateways or poolers. - Experience designing cache invalidation strategies at scale. - Experience with index recommendation, query-plan analysis or query optimisation tooling. - Experience validating technical changes through workload replay, shadow traffic or benchmarking. - Production experience with Prometheus, Grafana or OpenTelemetry. - Experience working with Kubernetes and cloud infrastructure. Technology - Go and Rust - PostgreSQL and MySQL - Kubernetes - AWS, GCP and Azure - Terraform - gRPC and REST - Prometheus, Grafana, Loki, Tempo and VictoriaMetrics - GitLab CI and Argo CD What we offer - €6,500 to €9,000 gross per month, depending on experience and level - Remote-first work environment - Equity options - Global team of cloud and infrastructure specialists - Fast feedback and short delivery cycles, with many feature projects completed within one to four weeks - 10% of working time for personal projects or professional development - Annual learning budget, including conferences and courses - Annual hackathon - Team-building budget and company events - Equipment budget - Additional days off Hiring process - Recruiter screening call - Hiring Manager interview - Technical system design interview - Live coding interview - Executive culture interview A background check may be conducted at the final stage through our third-party provider, Checkr. CAST AI does not provide visa sponsorship or work permits for this position. This opportunity is currently open to candidates residing in: Bulgaria, Croatia, Estonia, Greece, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia, Slovenia and Ukraine.