Senior Software Engineer, API Platform

Why Kimchi? Kimchi is the AI platform inside CAST AI. We started by helping companies run LLMs on their own Kubernetes clusters and now we're providing a managed variant of those same capabilities. Our Infrastructure today Multi-model inference (MiniMax, Kimi, GLM-5, Nemotron, DeepSeek) with intelligent routing, an OpenAI-compatible API and deployment ranging from our GPUs to your own VPC. The inference layer is the foundation and the API is what sits in front of it as the primary channel for broadly and reliably distributing our AI services and powers our own Kimchi harness. As a Senior Software Engineer, you will have the opportunity to work on different key features of our product. All of these are high-agency roles across multiple parts of the tech stack that minimize process friction that would otherwise prevent you from shipping. In every team you will own features end-to-end: design, implementation, testing, production rollout. Most projects ship in 1-4 weeks. You'll work directly with product and other engineering teams on problems that don't have textbook solutions. We are currently hiring Senior Software Engineers for the API Platform Team: Owns the inference API responsible for delivering our AI services across the world while making sure it's reliable and capable to scale in tandem with our company's growing ambitions, as well as our analytical platform, billing and role-based controls that enable our users to monitor and control their usage with ease - be it as a solo developer or a large enterprise. You'll own our infrastructure, datastores, analytics, observability and CI/CD pipeline. Responsibilities Develop with observability in mind, identify bottlenecks and optimize for performance. When p99 latency climbs, you find the cause through query profiles and flame graphs instead of raising the alert threshold.Design the datastores and distributed systems behind the inference API, and keep them reliable as usage scales from a solo developer to a large enterprise.Build the billing, usage metering, and role-based controls that let users monitor and govern their own consumption. Catch correctness problems where a wrong number costs you trust. Requirements Production experience with Go or Typescript is strongly preferred; candidates without either should demonstrate strong systems programming skills in a comparable language.Strong debugging, optimization, and performance-tuning skills – including query profiling, index design, and database performance tuning beyond ORM usage.Hands-on experience with cloud platforms (AWS, GCP, or Azure) and Kubernetes is a strong plusObservability tooling (Prometheus, Grafana, OpenTelemetry), CI/CD and DevOps practices experience.Startup mindset: adaptable, proactive, and comfortable with ambiguity.Strong English skills, both verbal and written.You've personally driven a complex project end-to-end. What’s in it for you? Competitive salary (€6,500 - €9,000 gross, depending on the level of experience).Enjoy a flexible, remote-first global environment.Collaborate with a global team of cloud experts and innovators, passionate about pushing the boundaries of Kubernetes technologyEquity options.Get quick feedback with a fast-paced workflow. Most feature projects are completed in 1 to 4 weeks.Spend 10% of your work time on personal projects or self-improvement. Learning budget for professional and personal development - including access to international conferences and courses that elevate your skills.Annual hackathon to spark new ideas and strengthen team bonds.Team-building budget and company events to connect with your colleagues.Equipment budget to ensure you have everything you need.Extra days off to help maintain a healthy work-life balance. Hiring process Screening call with RecruiterHiring Manager interviewTechnical interview (system design)Live codingCulture Check interview with an executive As part of our standard hiring process, we would like to inform you that a background check may be conducted at the final stage of recruitment through our third-party provider, Checkr. Please note that Cast AI does not provide any form of visa sponsorship/work permit.