Technical Staff Member - Post-Training & Reinforcement Learning

About SimileAt Simile, we are redefining how society’s most impactful decisions are made. Just as pilots and surgeons practice under controlled conditions, we believe that critical societal choices should not be made in untested environments.Our groundbreaking AI simulation of society, powered by generative agents modeled after real humans, is revolutionizing the field of AI-driven simulation. We are on a mission to accurately predict human behavior across diverse scenarios and scales.With $100 million in funding from renowned investors such as Index Ventures, Hanabi, A*, Bain Capital Ventures, and notable AI pioneers like Andrej Karpathy and Fei-Fei Li, we are poised for remarkable growth.

Join xAI's innovative Platform Security team as a Technical Staff Member, where you'll develop state-of-the-art security solutions to safeguard our Kubernetes infrastructure and enhance secure AI systems. In this role, you will design and implement AI-driven security tools, proactively tackle vulnerabilities, and advocate for secure engineering practices. Ideal candidates are passionate about impactful innovation, excel in writing clean and efficient code, and thrive in fast-paced environments, all while supporting xAI’s mission to create a trusted and secure global digital platform.

About SimileAt Simile, we believe in revolutionizing decision-making by simulating the complexities of society. Just as pilots and surgeons train in controlled environments, we aim to equip organizations with the ability to anticipate human behavior through advanced AI simulations. Our pioneering research has established a new frontier in AI-based modeling, allowing us to forecast human behavior across various scenarios and scales.With substantial backing of $100 million from prominent investors including Index Ventures and AI luminaries such as Andrej Karpathy and Fei-Fei Li, we are committed to pushing the boundaries of artificial intelligence.Join Our Infrastructure TeamThe Infrastructure team at Simile is crucial to our platform's success. We design and implement the foundational systems that enable our AI agents to function securely and efficiently on a large scale. We specialize in high-scale cloud networking and distributed systems, ensuring enterprise-grade privacy.Our Work is Organized Around Three Key Pillars:Cloud Foundation: Overseeing our multi-cloud environment (AWS/GCP) to ensure high availability and cost-efficiency through Infrastructure-as-Code.Enterprise Deployments: Creating streamlined pathways for VPC peering, PrivateLink, and BYOC (Bring Your Own Cloud) architectures tailored for our largest clients.Platform & Reliability: Developing CI/CD pipelines and observability stacks (including p99 latency tracking and SLOs) that empower our entire engineering organization to deliver safely and effectively.Role OverviewWe are on the lookout for a driven Infrastructure Engineer who is passionate about navigating the intricacies of modern deployment strategies. You will take charge of our infrastructure roadmap from conception through to operational execution, ensuring our platform remains resilient, compliant, and primed for global scalability.Key ResponsibilitiesArchitect Multi-Cloud Environments: Design and expand multi-region architectures across AWS and GCP, addressing global data residency and failover needs.Enhance Engineering Velocity: Collaborate with Product Engineering, Research, and Security teams to develop internal tools and paved pathways that accelerate development and empower engineering teams.

About UsAt vinci4d, we are pioneering a revolutionary co-pilot for hardware designers, aiming to empower 9 million mechanical engineers to accelerate their design processes by a factor of 1000.Our innovative approach involves developing a geometry and physics-driven foundation model tailored for diverse part designs.We are proud to have secured initial funding from Khosla Ventures, propelling us forward in our mission.About YouYou are a passionate Computational Fluid Dynamicist skilled in developing flow solvers for intricate geometrical applications. Your expertise encompasses external flows over dynamic vehicles (aircraft, missiles, automobiles), as well as fluid movement through machinery such as ducts, turbo-machinery, refrigeration systems, and computer heat sinks. Terms like conjugate heat transfer, multi-physics applications, and complex geometries excite you.Your ResponsibilitiesDesign, develop, and deploy simulation codes for single and multi-physics configurations, emphasizing Conjugate Heat Transfer.Optimize code performance on contemporary architectures, including GPUs.Implement advanced linear and nonlinear solvers to reduce time to solution.Collaborate in strategizing, planning product roadmaps, and prioritizing development alongside early customers and design partners.Develop and launch critical product features.Engage in continuous learning while creating products that resonate with engineers, gaining insights into entrepreneurship.

Mithril is building AI infrastructure to make GPU computing accessible for enterprises, AI startups, and research organizations. The company’s customers include LG AI Research, Saronic, and the Broad Institute. Mithril was founded by a former Google DeepMind research scientist and a Stanford CS PhD, and has raised $80 million in seed and Series A funding from Sequoia Capital, Lightspeed Venture Partners, and others. Platform revenue has grown more than sixfold in the past year. Fast Company recognized Mithril as the 8th Most Innovative Company in Artificial Intelligence for 2026. The team is transitioning from bare-metal operations to a cloud-native, multi-provider platform, introducing an auction and flexibility model. This is an opportunity to help shape the platform from its early stages. Role overview The Software Engineer - Technical Staff Member will work across three main areas: Consumption: Developer-facing product, billing, and API Platform: Orchestration and marketplace solutions Supply: Cloud provider integrations and capacity management Engineers at Mithril take on significant ownership, building features end-to-end that support critical customer workloads and drive revenue. The scope includes backend systems, marketplace logic, and customer interfaces. Architectural decisions here have a direct impact on Mithril’s growth and scalability. What makes this role unique This position blends deep systems work with product-facing challenges. Engineers contribute to the orchestration engine that manages GPU capacity across providers, as well as the interfaces customers use to reserve, bid, and utilize resources. The systems built in this role handle financial transactions, real workloads, and market mechanisms such as spot auctions, reservation pricing, and capacity allocation. For those interested in the mechanics of GPU infrastructure markets and building the technology behind them, this role offers direct involvement. Location This role is based in Palo Alto or the San Francisco Bay Area.

About UsIn a world where pilots and surgeons practice in simulated environments, we at Simile are pioneering the future by transforming how society's most critical decisions are modeled and understood.We have created the first AI simulation of society, filled with generative agents that reflect real human behavior. Our groundbreaking research has established the viability of AI-driven simulation and we are currently advancing a Foundation Model designed to predict human actions in diverse scenarios and at any scale.With $100M in funding from prominent investors such as Index Ventures, Hanabi, A*, Bain Capital Ventures, and leading AI figures like Andrej Karpathy and Fei-Fei Li, we are poised to revolutionize our field.Your OpportunityAs a Product Engineer - Member of the Technical Staff, you will be crucial in developing the platform that leverages our foundational model. This role is not limited to UI construction; it involves designing robust infrastructure and interfaces to facilitate complex multi-agent simulations for elite organizations worldwide.We seek full-stack engineers who can seamlessly integrate advanced AI research with production-ready enterprise software. You will architect and scale systems that empower clients to manage thousands of generative agents, observe emergent behaviors, and extract meaningful insights from simulated societies.Key Responsibilities:End-to-End Ownership: Lead the product development lifecycle for new enterprise solutions, from initial design through backend services to user-centric components and APIs.Collaborative Product Development: Work closely with product managers, designers, and customers to simplify complex human behavior simulations into intuitive interfaces.System Evolution: Develop and refine systems that enhance customer workflows, ensuring reliability, performance, and scalability as we model human behavior on a global scale.Technical Excellence: Write clean, well-tested code and engage in thorough code reviews to uphold high standards of system quality and safety in production.Pragmatic Shipping: Balance the need for a sound technical architecture with the urgency to deliver incrementally and learn from real-world applications.

About xAIAt xAI, we are on a mission to develop advanced AI systems that enhance our understanding of the universe and help humanity achieve its knowledge goals. Our dedicated team is small yet highly driven, emphasizing engineering excellence. We value individuals who thrive on curiosity and are eager to tackle challenges head-on. With a flat organizational structure, we empower all employees to take initiative and contribute meaningfully to our mission. Exceptional work ethic, prioritization skills, and strong communication abilities are essential for success in our collaborative environment. About the RoleWe are in search of outstanding engineers eager to embark on an innovative project aimed at integrating Grok into every aspect of our Advertising Platform. We seek individuals with extensive experience in developing high-performance advertising products and systems at scale, encompassing bidding, auction, marketplace dynamics, ranking, prediction, and product functionalities. Your expertise will help us leverage xAI’s technology stack to revolutionize our advertising solutions.Your ResponsibilitiesUtilize state-of-the-art Grok models to enhance all facets of our advertising stack, including candidate selection, ranking, auctions, campaign optimization, creative development, and improving the advertiser experience.Take ownership of systems and products that drive significant revenue for the company.Who You AreYou possess 3+ years of industry experience in creating large-scale, high-throughput, AI-driven advertising solutions.Technical ProficienciesProficient in Python, Jax, and Rust.LocationOur engineering team is based in Palo Alto, CA. While we typically work from the office five days a week, we offer flexible work-from-home options when needed.Interview ProcessUpon submitting your application, our team will review your resume and documentation of your outstanding work. If your application meets our criteria...

About xAIAt xAI, our vision is to develop AI systems that deeply comprehend the universe and assist humanity in its quest for understanding. Our team is a close-knit, highly driven group committed to engineering excellence. We welcome individuals who relish challenges and thrive on curiosity. Operating within a flat organizational structure, we expect all employees to be hands-on contributors to our mission. Proactive leadership is recognized, and a strong work ethic combined with exceptional prioritization skills is essential. Effective communication is crucial, as employees must be able to share knowledge clearly and precisely with colleagues.ROLE OVERVIEW:Join our Grok Voice Model team to engineer the leading voice AI technology. We aim to facilitate seamless, natural, low-latency spoken interactions that are expressive, multilingual, and reliable across devices and real-time applications. We manage the entire training pipeline, encompassing extensive data curation, high-quality audio processing, cutting-edge speech-language pre-training, and rigorous post-training to maximize quality, speed, and stability.Our aspiration is to make conversing with AI feel like engaging with the most charming, knowledgeable, and kind individual imaginable. We are in search of exceptionally intelligent, execution-focused engineers to help us achieve this goal.

About Us At vinci4d, we are revolutionizing the hardware design landscape with our cutting-edge AI assistant, aimed at empowering engineers to accelerate their design iterations by a staggering 1000 times.Our innovative foundation model, driven by geometry and physics, is tailored for each category of part design.We are on the lookout for passionate individuals who thrive on product development to enhance our Minimum Viable Product (MVP).Your ResponsibilitiesAs a pivotal member of our team, you will design and develop the essential pipelines and tools that transform our vision into reality. Your contributions will significantly expedite our development processes by facilitating smooth transitions from code development to deployment. Key responsibilities include:Enhancing product features for scalability and developing advanced APIs to support intricate engineering workflows.Establishing and integrating LLM or VLM infrastructure.Implementing an MLOps framework for training deep learning models using geometry and physics data.Collaborating with early customers and design partners to strategize and prioritize the development roadmap.Building and deploying critical product features.Gaining invaluable experience while creating products that resonate with engineers, and learning about the entrepreneurial journey.QualificationsA minimum of 6 years in developing and delivering features within the high-performance computing domain.Expertise in C++, Python, or any relevant language necessary for system setup, along with familiarity with tools such as gRPC, Protocol Buffers, Docker, Kubernetes, and Bazel.Experience with cloud computing for data generation, scraping, and assisting data science teams in model training with MLOps is a plus.CUDA experience is desirable but not mandatory.Frontend development experience is a bonus.Prior experience in a startup environment will be highly valued.You’ll Thrive in This Role If YouAre enthusiastic about entrepreneurship and the process of transforming ideas from concept to reality.

Join SpaceX as a Member of Technical Staff, where you will play a crucial role in supporting government initiatives and projects that require top-secret clearance. Your expertise will contribute to the development of cutting-edge technologies that are transforming space exploration and enabling humanity's future in space.

Join Our Team at SimileAt Simile, we are revolutionizing decision-making in society by providing AI simulations that accurately model human behavior. Just as pilots and surgeons rely on simulations for training, we believe that businesses deserve the same rigor when making high-stakes decisions.Our groundbreaking work has led to the creation of the first AI simulation of society, featuring generative agents that reflect real human experiences. Backed by $100 million from top investors, including Index Ventures and renowned AI experts, we are on a mission to predict human behavior with unparalleled accuracy.The RoleAs an Applied Research Engineer and Member of Technical Staff (MTS), you will be integral in refining our models of human behavior. With a strong emphasis on scientific rigor, you will participate in the entire research cycle—from designing experiments to implementing them in production systems that influence real-world decisions.Your Responsibilities Will Include:Data Insight Extraction: Analyze extensive proprietary datasets, including unstructured interviews and behavioral data, to uncover meaningful insights.Hardware Proficiency: Develop and optimize algorithms for cutting-edge NVIDIA hardware, conducting experiments that inform our model training.Scientific Leadership: Design thorough evaluations that validate our behavioral simulations against industry standards.Pushing Boundaries: Engage with the latest research in simulation and AI, continuously enhancing our methodologies and documentation.

Join xAI as a Member of the Technical Staff specializing in Inference Engineering. Our mission is to engineer cutting-edge AI systems that enhance humanity's understanding of the universe. We are a dynamic, compact team dedicated to excellence, where each member is encouraged to take initiative and contribute significantly to our objectives. The ideal candidate will thrive in a collaborative environment, showcasing their expertise in optimizing model inference and developing robust systems capable of serving billions of users. If you are passionate about pushing the boundaries of AI technology and enjoy tackling complex challenges, we want you on our team.

Join our innovative team at Elorian AI Inc. as we spearhead the development of cutting-edge visual intelligence solutions. We are on the lookout for exceptional researchers and engineers who are passionate about advancing the field of artificial intelligence. If you are committed to excellence and thrive in a dynamic environment, we would love to hear from you.

Join SpaceX as a Platform Engineer, where you will contribute to the development and maintenance of our cutting-edge technology platforms. This role entails working with a talented team to build robust systems that support our missions in space exploration. Your expertise and innovation can help us push the boundaries of what is possible.

Join our innovative team at xai as a Member of Technical Staff specializing in Web Foundations. In this role, you will collaborate with cross-functional teams to develop and enhance our web infrastructure, ensuring high performance and scalability. You will have the opportunity to leverage cutting-edge technologies to build and maintain robust web applications that serve our global user base.

Join our innovative team at xai as a Member of the Technical Staff for our X Core Product. In this pivotal role, you will leverage your expertise to drive cutting-edge solutions that enhance product performance and user experience. Collaborate with cross-functional teams to design, implement, and optimize system architectures while contributing to the development of next-generation technologies.

SpaceX seeks a Technical Staff Member to join its government sector projects in Palo Alto, CA. This position focuses on designing, developing, and implementing technical solutions for government clients, with a strong emphasis on aerospace technology. The work directly supports SpaceX’s mission to advance multi-planetary life. Key responsibilities Develop and deliver technical solutions that meet government requirements Collaborate with a team to solve complex engineering problems Contribute expertise to projects that extend the frontiers of aerospace technology Location This role is based in Palo Alto, CA.

About xAIAt xAI, our mission is to develop AI systems that genuinely comprehend the universe and support humanity's quest for knowledge. We pride ourselves on having a compact, highly driven team dedicated to engineering excellence. Our environment is perfect for individuals who relish challenges and flourish through curiosity. We embrace a flat organizational structure where every employee is encouraged to be proactive and to directly contribute to our mission. Leadership opportunities are awarded to those who demonstrate initiative and consistently achieve outstanding results. Strong work ethic and effective prioritization skills are key attributes we value. Additionally, all team members must possess excellent communication skills to share insights and knowledge clearly and concisely with their colleagues.About the RoleWe are looking for talented Applied Engineers to join a pivotal project that serves around 600 million users monthly. This is a unique opportunity for professionals with an engineering or scientific background to leverage their expertise in recommendation systems, ranking algorithms, search technologies, and more. You will be at the crossroads of cutting-edge AI development and tangible real-world impact, enhancing our ability to connect users with relevant content, accounts, and experiences.What You'll DoDesign and architect innovative recommendation algorithms for diverse product surfacesUtilize xAI’s extensive infrastructure and AI tools to significantly enhance user experiencesDevelop data pipelines and training jobs that continuously adapt from product dataIterate and refine algorithms using real-time user feedback through experimentationEnsure the scalability and efficiency of machine learning systemsWho You AreFamiliarity with data infrastructure technologies such as Kafka, Clickhouse, and SparkProven experience in implementing recommender systems and/or deep learning applications at scaleProficient in one or more deep learning software frameworks, such as JAX or PyTorchExceptional candidates may have experience in writing CUDA kernels

About xAI xAI is focused on building advanced AI systems capable of understanding complex problems and supporting humanity’s search for knowledge. The team values curiosity, hands-on problem solving, and strong communication. Leadership comes from initiative and results, not hierarchy. Team members share insights openly and work closely together. Role Overview: Technical Staff Member - Multimodal Intelligence This position sits within the multimodal team at xAI in Palo Alto, CA. The goal: push the boundaries of multimodal intelligence by building systems that understand and generate image, video, audio, and text data. What You Will Do Work on every stage of the multimodal pipeline, including data acquisition, tokenizer training, large-scale pre-training, infrastructure scaling, and tooling. Develop and deliver end-to-end product experiences that showcase advanced multimodal capabilities. Collaborate with teams across xAI to advance multimodal reasoning, world modeling, tool use, and interactive human-AI collaboration. Help build models that perceive, understand, and interact with the world in real time. Team Culture Flat structure: leadership is earned by initiative and performance. Open communication and collaboration are essential. Curiosity and a drive to tackle tough challenges are highly valued.