---
title: 'Software Engineer - Training/Inference (C++) at xAI'
canonical: 'https://feeny.ai/job/software-engineer-training-inference-c-xai-palo-alto-6t323knf3tr0'
type: 'job'
last_seen: '2026-10-19'
---

# Software Engineer - Training/Inference (C++) at xAI

- **Company:** xAI
- **Location:** Palo Alto, CA / Seattle, WA
- **Posted:** 2024-10-05
- **Last confirmed live:** 2026-10-19
- **Apply:** https://job-boards.greenhouse.io/xai/jobs/4533894007

## Job description

SpaceX was founded under the belief that a future where humanity is out exploring the stars is fundamentally more exciting than one where we are not. Today, SpaceX is actively developing the technologies to make this possible, with the ultimate goal of making life multiplanetary and expanding consciousness to the stars.

SpaceXSI is building Super Intelligence to help humanity understand the universe. Our teams are building the full Super Intelligence stack: from our Colossus supercomputers, to Grok models, to our suite of applications, including Grok Bot, Grok Build, Grok Imagine, Grok Voice, and X. We're creating a powerful flywheel where more compute trains better models, better models power more useful products, and what we learn from people using those products shapes what we build next.

About the Role:

- We are building the high-performance inference platform that serves Grok to millions of users every day with lightning speed and perfect reliability.
- As a Member of Technical Staff - Inference, 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 (GPU kernels, quantization, speculative decoding, 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 workloads.
- Build reliable, high-concurrency serving systems that serve billions of users with 100% uptime, 0% error rate, and excellent tail latency.
- Benchmark, 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 kernels.
- Create robust CI/CD infrastructure for seamless endpoint deployment, image publishing, and inference engine updates.
- Accelerate research on scaling test-time compute, RL rollout, and model-hardware co-design for next-generation systems.

## BASIC QUALIFICATIONS:

- Deep low-level systems programming (C/C++ or Rust)
- Experience with large-scale, high-concurrent production serving.
- Experience with GPU inference engines (vLLM, SGLang, Triton, TensorRT-LLM, etc.).
- Strong background in system optimizations: batching, caching, load balancing, parallelism.
- Low-level inference optimizations: GPU kernels, code generation.
- Algorithmic inference optimizations: quantization, speculative decoding, distillation, low-precision numerics.
- Experience with testing, benchmarking, and reliability of inference services.
- Experience designing and implementing CI/CD infrastructure for inference.

## COMPENSATION AND BENEFITS:

$180,000 - $440,000 USD

Base 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](https://x.ai/legal/recruitment-privacy-notice).

## About xAI

## Company Overview
- **One‑liner**: xAI builds artificial intelligence systems to accelerate human scientific discovery and “understand the universe,” with products spanning frontier reasoning models, real‑time voice, and generative media.
- **Entity Type**: Private (last funding round: Series E, January 2026; acquired by SpaceX in February 2026)
- **Headquarters**: Palo Alto, California, USA (additional offices in Seattle, WA; Memphis, TN; London, UK)
- **Founded**: 2023
- **Founders**: Elon Musk

## Core Business
- Primary industry: Artificial Intelligence (AI research, large language models, voice AI, generative media)
- Target customers: B2B (developers via API), B2C (consumers via Grok on 𝕏, SuperGrok subscriptions), Enterprise & Government (xAI for Government)
- Mission: “To understand the universe” – building AI that extends what humanity can know and do.

## Products & Services
- **Grok (base models)** : A conversational AI assistant modeled after *The Hitchhiker’s Guide to the Galaxy*, available on the 𝕏 platform and via API.
- **Grok 4 / Grok 4 Heavy**: The most intelligent reasoning models, featuring native tool use and real‑time search integration (SuperGrok and Premium+ tiers).
- **Grok Voice Agent API / Voice Agent Builder**: Create custom voice agents in under two minutes (no‑code) – includes speech‑to‑text, text‑to‑speech, custom voice cloning, and multilingual support.
- **Grok Imagine API**: State‑of‑the‑art video generation API (quality, cost, latency).
- **Grok‑1.5 / Grok‑2 / Grok‑2 mini**: Earlier model releases with improved reasoning and 128K context length.
- **PromptIDE**: An integrated development environment for prompt engineering and interpretability research.
- **xAI for Government**: A suite of frontier AI products tailored for U.S. government customers.
- **Colossus Supercomputer**: 200,000‑GPU cluster built in 122 days, used for training xAI models; now also leased to Anthropic (Colossus 1 agreement).

All products are delivered as SaaS, API, and model weights (open‑source release of Grok‑1).

## Market Standing
- **Valuation / Funding**: 
  - Series B (May 2024): $6 B 
  - Series C (Dec 2024): $6 B (led by A16Z, BlackRock, Fidelity, Kingdom Holdings, Lightspeed, MGX, Morgan Stanley, OIA, QIA, Sequoia, Valor, Vy Capital, others)
  - Series E (Jan 2026): $20 B
  - Acquisition by SpaceX announced Feb 2, 2026 (terms not disclosed).
- **Key Metric**: Total disclosed funding ~$32 B; annual revenue not publicly available.
- **Notable Investors/Partners**: A16Z, BlackRock, Fidelity, Sequoia Capital, Morgan Stanley, Kingdom Holdings, Lightspeed, MGX, Valor Equity Partners, Vy Capital, Anthropic (Colossus deal), U.S. Department of War (selected Dec 2025).
- **Growth Signals**: 
  - Rapid scaling from founding to 200K‑GPU cluster in 122 days.
  - Over 214 open roles listed on Greenhouse as of mid‑2026.
  - #1 on Big Bench Audio (Grok 4 audio performance).
  - Expanded into voice agents, video generation, and government verticals within 3 years.
  - Acquisition by SpaceX signals deep integration with space‑tech resources.

## Competitive Advantages
- **Compute infrastructure**: Colossus supercomputer – one of the largest GPU clusters in existence, enabling faster training and larger models.
- **Model performance**: Grok 4 claims “most intelligent model in the world” with top benchmarks (Big Bench Audio #1).
- **Vertical integration**: Tight coupling with 𝕏 platform for data, distribution, and real‑time world knowledge.
- **Speed of execution**: “Move quickly and fix things” culture; built Colossus in 122 days.
- **Government contracts**: Early access to public‑sector AI markets (U.S. Department of War).
- **Talent density**: Small, focused team of researchers and engineers; in‑person work accelerates iteration.

## Strategic Focus
- **Continue advancing frontier reasoning** (Grok 4 Heavy, next‑gen models).
- **Expand voice and multimodal APIs** for developers (Voice Agent Builder, Custom Voices Library).
- **Deepen government / defense partnerships** (xAI for Government, Department of War).
- **Scale infrastructure** post‑acquisition via SpaceX resources.
- **Remain “open” where strategic** (open‑source release of Grok‑1 weights).

## Why Work Here
- **Culture**: “Ambitious goals, fast execution” – rejects consensus in favor of first‑principles reasoning. In‑person work prioritized (Palo Alto, Seattle, Memphis, London).
- **Benefits**: 
  - Competitive cash + equity compensation.
  - Comprehensive medical, dental, vision, disability, life insurance.
  - 401(k) plan, fertility benefits, flexible vacation.
  - Visa sponsorship offered.
- **Engineering culture**: No recruiters for assessments – applications reviewed directly by technical team. Interview process: application → screening → technical interviews → offer.
- **Mission‑driven**: Opportunity to work on frontier AI models that aim to “advance humanity.”
- **Perks**: In‑person collaboration, fast‑paced environment, ownership of meaningful projects.

## Sources
1. [x.ai/company](https://x.ai/company)
2. [x.ai/careers](https://x.ai/careers)
3. [job-boards.greenhouse.io/xai](https://job-boards.greenhouse.io/xai)
4. [x.ai/news](https://x.ai/news)
5. [x.ai/careers/open-roles](https://x.ai/careers/open-roles)

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