Senior Software Engineer - Product Foundations

About the role

Cast AI is an automation platform that runs cloud-native and AI infrastructure at scale, embedding autonomous decision-making into Kubernetes and cloud environments. It is looking for a Senior Software Engineer for its Product Foundations team, which works on the trust and accounting layer behind the platform: authentication, authorization, SSO, billing, audit trails, notifications, feature flags, real-time cloud pricing tracking and reporting. The position is remote-first and open to candidates living in the listed countries; onboarding takes place in Vilnius.

Key responsibilities

• Design, build and operate backend services in Go that other teams and customers depend on being correct.
• Own features end-to-end, from design through implementation, testing and production rollout.
• Debug complex production issues involving security, money or trust-critical flows.
• Collaborate with product and other engineering teams on problems without textbook solutions.
• Contribute to product direction and backlog.

Required profile

• Strong software engineering fundamentals and clean, maintainable code.
• Experience building or operating trust-critical systems such as authentication/authorization, billing or financial data.
• Production experience with Go strongly preferred; comparable systems programming skills accepted.
• Hands-on Kubernetes experience and experience with AI coding agents and agentic workflows.
• Complex project ownership, strong English, startup mindset, and willingness to join on-call rotations.

Required skills

• Go, Kubernetes, Terraform, PostgreSQL, ClickHouse, GCP Pub/Sub, gRPC and REST.
• Nice to have: multi-tenant identity systems, SAML/OIDC/SCIM, cloud pricing APIs, time-series data, observability tooling (Prometheus, Grafana, OpenTelemetry), CI/CD and GitOps.

What we offer

• Salary of EUR 6,500 to 9,000 gross plus separate on-call pay.
• Flexible, remote-first environment with equity options.
• 10% of work time for personal projects, learning budget, annual hackathon, team-building budget and equipment budget.
• Extra days off; travel to Vilnius for onboarding covered by the company.