Backend Engineer responsible for building and owning the xAI API that serves models to developers worldwide. This includes end-to-end system ownership for high-throughput, low-latency, and highly available inference, covering model serving infrastructure, request routing, SDK development, rate limiting, observability, and scaling. Requires expertise in Rust or C++, distributed systems, and observability, with preferred experience in LLM inference engines, serving frameworks, and agent orchestration.