# Sr. Model Engineer, Multimodal Understanding at xAI

> United States · Senior · Software engineering · open. Source: https://alderhq.app/jobs/greenhouse%3Axai%3A5111374007 (read 2026-11-04).

## Facts (observed)

- Company: [xAI](https://alderhq.app/companies/xai)
- Location text: Palo Alto, CA; Palo Alto, CA
- Where it can be done from (inferred): United States (evidence: "Location: Palo Alto, CA; Palo Alto, CA")
- Posted: 2026-04-17 (201 days ago)
- First seen by alder: 2026-11-02 · last verified: 2026-11-04
- Reposted: 0 times · edited: 0 times
- Apply on the employer's site: https://job-boards.greenhouse.io/xai/jobs/5111374007
- Skills listed (inferred): Python, Rust, C++, PyTorch, Distributed systems

## Pay and sponsorship

- Posted pay: not posted
- Market band for similar posted roles (SF Bay Area, n 839): p25 $183k, median $206k, p75 $229k

## Description (the employer's text)

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.

### SR. MODEL ENGINEER, MULTIMODAL UNDERSTANDING

You will join the multimodal team to push toward superhuman multimodal intelligence. Advance understanding and generation across modalities—image, video, audio, and text—spanning the full stack: data curation/acquisition, tokenizer training, large-scale pre-training, post-training/alignment, infrastructure/scaling, evaluation, tooling/demos, and end-to-end product experiences.

Collaborate cross-functionally with pre-training, post-training, reasoning, data, applied, and product teams to deliver frontier capabilities in multimodal reasoning, world modeling, tool use, agentic behaviors, and interactive human-AI collaboration. Contribute to building models that can see, hear, reason about, and interact with the world in real time at unprecedented levels.

### RESPONSIBILITIES

- Design, build, and optimize large-scale distributed systems for multimodal pre-training, post-training, inference, data processing, and tokenization at web/petabyte scale
- Develop high-throughput pipelines for data acquisition, preprocessing, filtering, generation, decoding, loading, crawling, visualization, and management (images, videos, audio + text)
- Advance multimodal capabilities including spatial-temporal compression, cross-modal alignment, world modeling, reasoning, emergent abilities, audio/image/video understanding & generation, real-time video processing, and noisy data handling
- Drive data quality and studies: curation (human/synthetic), filtering techniques, analysis, and scalable pipelines to support trillion-parameter models
- Create evaluation frameworks, internal benchmarks, reward models, and metrics that capture real-world usage, failure modes, interactive dynamics, and human-AI synergy
- Innovate on algorithms, modeling approaches, hardware/software/algorithm co-design, and scaling paradigms for state-of-the-art performance
- Build research tooling, user-friendly interfaces, prototypes/demos, full-stack applications, and enable rapid iteration based on feedback
- Work across the stack (pre-training → SFT/RL/post-training) to enable reasoning, tool calling, agentic behaviors, orchestration, and seamless real-time interactions
### BASIC QUALIFICATIONS

- Experience writing production-quality code in Python, PyTorch, JAX, Rust, or C++
- Experience training large models (e.g., pretraining, post-training, fine-tuning, or RL training of neural networks with 1B+ parameters)
### PREFERRED SKILLS AND EXPERIENCE

- Expert-level proficiency in Python (core language), with strong experience in at least one of: JAX / PyTorch / XLA
- Proven track record building or optimizing large-scale distributed ML systems (training/inference optimization, GPU utilization, multi-GPU/TPU setups, hardware co-design)
- Deep experience designing and running data pipelines at scale: curation, filtering, generation, quality studies, especially for noisy/real-world multimodal data
- Strong fundamentals in evaluation design, benchmarks, reward modeling, or RL techniques (particularly for interactive/agentic behaviors)
- Proactive self-starter who thrives in high-intensity environments and is passionate about pushing multimodal AI frontiers
- Willingness to own end-to-end initiatives and do whatever it takes to deliver breakthrough user experiences

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Data: alder (https://alderhq.app). Cite https://alderhq.app/jobs/greenhouse%3Axai%3A5111374007 and the date you read it. Observed facts come from the employer's own listing; location reach, level, family and skills are inferences.