Sr. Software Engineer, Training/Inference (C++)

SR. SOFTWARE ENGINEER, TRAINING/INFERENCE (C++)At SpaceXSI we are building the high-performance inference platform that serves Grok to millions of users every day. As a Software Engineer, Training/Inference (C++), you will design and optimize large-scale model serving systems end-to-end.

You will own everything from distributed infrastructure - global KV cache, continuous batching, load balancing, auto-scaling - to deep low-level optimizations, including GPU kernels, quantization, speculative decoding, and tail latency. This is a high-impact role where your work directly determines how fast and reliably users interact with Grok at massive scale.Responsibilities:Architect and implement scalable distributed infrastructure for model serving (load balancing, auto-scaling, batch scheduling, global KV cache)Optimize latency and throughput of model inference under real production workloadsBuild and operate high-concurrency serving systems with excellent tail latency and high reliability at the scale required to serve millions of usersBenchmark, fine-tune, and accelerate inference engines (including low-level GPU kernel work and code generation)Develop custom tools to trace, replay, and fix issues across the full stack — from orchestration down to GPU kernelsCreate robust CI/CD infrastructure for seamless endpoint deployment, image publishing, and inference engine updatesAccelerate research on scaling test-time compute, RL rollout, and model-hardware co-design for next-generation systemsBasic Qualifications:Bachelor's degree in computer science, computer engineering, or science discipline5+ years of experience with low-level system programming experience in C/C++ or RustPreferred Skills and Experience:Experience with large-scale, high-concurrent production servingExperience with GPU inference engines (e.g., vLLM, SGLang, Triton, TensorRT-LLM)Strong background in system optimizations: batching, caching, load balancing, parallelismLow-level inference optimizations: GPU kernels, code generationAlgorithmic inference optimizations: quantization, speculative decoding, distillation, low-precision numericsExperience with testing, benchmarking, and reliability of inference servicesExperience designing and implementing CI/CD infrastructure for inferenceCompensation and Benefits:$220,000 - $357,000 USDBase salary is just one part of our total rewards package at SpaceXSI, which also includes equity, comprehensive medical, vision, and dental coverage, access to a 401(k) retirement plan, short & long-term disability insurance, life insurance, and various other discounts and perks.SpaceXSI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.