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
• Experience leading major improvements in model capabilities through better data, modeling, algorithms, or scaling
• Familiarity with state-of-the-art in multimodal LLMs, scaling laws, tokenizers, compression techniques, reasoning, or agentic systems
• Proficiency in Rust and/or C++ for performance-critical components
• Hands-on work with large-scale orchestration tools such as Spark, Ray, or Kubernetes
• Background building full-stack tooling: performant interfaces, real-time research demos/apps, or end-to-end product ownership
• Passion for end-to-end user experience in interactive, real-time multimodal AI systems

COMPENSATION AND BENEFITS:

$180,000 - $400,000 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.