Member of technical staff (Infrastructure) - London

H

About H: H exists to push the boundaries of superintelligence with agentic AI. By automating complex, multi-step tasks typically performed by humans, AI agents will help unlock full human potential. H is hiring the world’s best AI talent, seeking those who are dedicated as much to building safely and responsibly as to advancing disruptive agentic capabilities. We promote a mindset of openness, learning, and collaboration, where everyone has something to contribute. About the Team: The Agent team defines new learning algorithms and agent paradigms to push the frontiers of agentic systems. We build upon foundation models and reinforcement learning to develop new approaches to train artificial general agents and work closely with the LLM/VLM and Safety teams to explore new directions. This is a heavily engineering-focused role embedded within the research team. You will be responsible for defining the architecture and building the robust, scalable systems that underpin our research efforts. Your work will translate cutting-edge research concepts into high-performance, production-quality platforms, enabling the next generation of agentic AI. Key Responsibilities: * Research & Leadership: Design and develop new agents, proposing new research directions, e.g., combining state-of-the-art RL with foundation models (LLMs/VLMs). * Algorithm & Systems Design: Design, implement, and scale complex, high-performance systems for training large-scale agents. This includes both the foundational infrastructure and the novel algorithms, reward models, and sophisticated training environments. * Research-to-Production: Collaborate closely with researchers and engineers to implement, test, and productionize new agent logics, learning algorithms, and system architectures. * Evaluation & Reliability: Create, manage, and scale massive benchmarks and evaluation systems to rigorously track agent capabilities. You will own system reliability, scalability, and observability for our entire research infrastructure. * Mentorship & Standards: Mentor and guide other engineers and researchers on the team, fostering technical excellence. You will establish and enforce engineering standards, tooling, and best practices for both code and research design. * Innovation: Conduct thorough code and design reviews, champion technical innovation, and proactively address technical debt to accelerate the R&D lifecycle. Requirements: * Technical Skills: * Senior Experience: Previous demonstrable role(s) as a Staff, Principal, or Senior Engineer (or equivalent Research Scientist) in a Frontier AI Lab with a proven track record of leading complex, end-to-end AI/ML projects from conception to production. * Education / Publication: Preferably PhD (or equivalent research experience) in Machine Learning, Computer Science, or a related field, preferably with a strong publication record (e.g., NeurIPS, ICML, ICLR) in Computer Science. * Core Expertise: Deep theoretical and practical expertise in Agentic AI and proven experience building, scaling, and shipping solutions involving foundation models (LLMs/VLMs). * Soft Skills: * Collaborative: Enjoys collaboration and thrives in a teamwork-oriented, fast-paced research environment. * High-Impact Communicator: Possesses impactful communication skills, with the ability to bridge the gap between research and engineering and articulate complex ideas clearly. * Mission-Driven: Genuinely eager to explore and solve the new engineering and research challenges at the frontier of agentic AI. * Bonus Skills: * Practical experience applying Reinforcement Learning to systems built on Large Language Models (LLMs). * Experience with distributed systems or cloud computing, preferably in AWS. * Familiarity with building complex simulation environments for agent training. * Experience with LLM training or fine-tuning. * Experience developing large-scale evaluation and benchmarking systems for AI models. * Experience in an agentic framework (e.g., LangChain, AutoGen, CrewAI, OpenAI SDK). * Expertise in system architecture, instrumentation, observability, and monitoring for complex, high-performance systems. Location: * Paris or London. * This role is hybrid, and you are expected to be in the office 3 days a week on average. * Please expect some travel between offices on a reasonable cadence (e.g., every 4-6 weeks). What We Offer: * Join the exciting journey of shaping the future of AI, and be part of the early days of one of the hottest AI startups. * Collaborate with a fun, dynamic, and multicultural team, working alongside world-class AI talent in a highly collaborative environment. * Enjoy a competitive salary. * Unlock opportunities for professional growth, continuous learning, and career development. If you want to change the status quo in AI, join us.

H

About H: H exists to push the boundaries of superintelligence with agentic AI. By automating complex, multi-step tasks typically performed by humans, AI agents will help unlock full human potential. H is hiring the world’s best AI talent, seeking those who are dedicated as much to building safely and responsibly as to advancing disruptive agentic capabilities. We promote a mindset of openness, learning, and collaboration, where everyone has something to contribute. About the Team: The Infrastructure team aims to make it seamless for our researchers and engineers to access and use the infrastructure they need to do their job. The team also ensures the underlying infrastructure for our public services is robust, reliable and scalable. Members of the Infra team are uniquely positioned to impact all areas of H, from building everything from our foundational models to our agents, all the way to our public services. Key Responsibilities: * Designing and managing the infrastructure to support * Research efforts in Model and Agent development incl. training infrastructure, data pipelines and inference. * Product Engineering efforts on H Company’s agent platform including client-facing APIs and agent runtimes within various deployment scenarios (multi-tenant and on-prem). * Setup and maintain observability and monitoring strategies. Requirements: * MUST HAVE * Observability and monitoring (Datadog, Prometheus, Grafana, …) * Good knowledge of a modern programming language (ideally Python or JS/Typescript) * NICE TO HAVE * ML Ops or Data Engineering * Experience architecting and deploying distributed systems on public cloud (AWS, Azure, GCP) * Containerization and orchestration tools (Docker, Kubernetes, …) * Infrastructure as code (CDK, Terraform, ...) * CICD management experience (Github Actions, Gitlab CI, TeamCity, ...). Location: * Paris or London. * This role is hybrid, and you are expected to be in the office 3 days a week on average. What We Offer: * Join the exciting journey of shaping the future of AI, and be part of the early days of one of the hottest AI startups * Collaborate with a fun, dynamic and multicultural team, working alongside world-class AI talent in a highly collaborative environment * Enjoy a competitive salary * Unlock opportunities for professional growth, continuous learning, and career development If you want to change the status quo in AI, join us.

xAI

SpaceXAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge. Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. We operate with a flat organizational structure. All employees are expected to be hands-on and to contribute directly to the company’s mission. Leadership is given to those who show initiative and consistently deliver excellence. Work ethic and strong prioritization skills are important. All employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: The Sandbox service team at SpaceXAI builds and maintains a secure, scalable system that gives our models safe, controlled access to computational environments. This infrastructure powers critical workloads across training and product, enabling models to run code, build software, interact with tools, and even control applications with user interfaces. We provision containers and virtual machines on large-scale clusters, granting models interactive control over these remote environments. Our work spans the full stack: from orchestrating massive jobs and resource scheduling at the cluster level, to fine-tuning filesystem performance on nodes. The Sandbox service enables Grok to safely run and test code in real-time for user queries, and supports reinforcement learning in training, where models interactively explore tools ranging from compilers to productivity apps. BASIC QUALIFICATIONS: * Expert knowledge of Rust, C++ or Go * Familiarity with Python * Deep experience with either Linux or Windows systems (familiarity with both is a strong plus) * Experience with virtualisation and containerisation technologies (e.g., cgroups, KVM, gVisor, QEMU) * Solid knowledge of the networking stack COMPENSATION AND BENEFITS: £107,000 - £262,000 GBP Base salary is just one part of our total rewards package at SpaceXAI, which also includes equity, comprehensive healthcare and dental coverage, cash plan, income protection, life insurance, and various other discounts and perks. SpaceXAI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.