Technical Staff Member - Reasoning

About H:H is at the forefront of advancing superintelligence through agentic AI. Our mission is to automate complex, multi-step tasks usually undertaken by humans, empowering AI agents to unlock the full potential of human capabilities.We are on the lookout for the brightest AI minds who are as committed to building safely and responsibly as they are to pushing the boundaries of disruptive agentic technologies. At H, we foster a culture of openness, continuous learning, and collaboration, where every voice contributes to our shared success.About the Team: The Infrastructure team is dedicated to providing seamless access to the necessary infrastructure for our research and engineering teams. We ensure that the foundational infrastructure for our public services is robust, reliable, and scalable, positioning Infra team members to influence every aspect of H, from foundational model development to agent creation and public service delivery.Key Responsibilities:Design and manage infrastructure to support:Research initiatives in model and agent development, including training infrastructure, data pipelines, and inference capabilities.Product engineering efforts on H's agent platform, encompassing client-facing APIs and agent runtimes across multiple deployment scenarios (multi-tenant and on-premises).Establish and maintain observability and monitoring strategies.

Join xai as a Technical Staff Member focusing on Model Training. In this role, you will collaborate with a talented team to develop and optimize machine learning models that drive innovative solutions. Your expertise will contribute to enhancing the performance of our systems and delivering impactful results.

Join Cohere as a valued member of our technical staff, focusing on the safety of our agents. In this critical role, you will be responsible for designing, implementing, and maintaining safety protocols that ensure the integrity and security of our systems. Collaborate with cross-functional teams to develop innovative solutions that enhance agent safety and improve operational efficiency.

About the Role XAI is hiring a Member of Technical Staff for the X Money team in London. This role focuses on building and improving financial technology products that support the company's mission. What You Will Do Design, develop, test, and deploy software features for the X Money platform Work closely with engineers and other professionals to deliver reliable and secure solutions Help ensure the platform meets standards for performance, scalability, and security Who We’re Looking For Technical staff with a strong interest in financial technology Comfortable taking on challenging projects and collaborating with others Ready to contribute ideas and take ownership of solutions Location This position is based in London, UK.

Location: LondonCompany: H About H H is focused on building agentic AI that automates complex, multi-step tasks typically handled by people. The company’s goal is to help individuals achieve more by creating superintelligent systems that work safely and responsibly. H values openness, continuous learning, and collaboration. Every team member’s input matters here. About the Models Team The Models team develops the core models that power H’s agentic AI technology. This group works on training methods to boost model performance and efficiency, especially for agent-driven applications where inference costs matter. Projects span Large Language Models (LLMs) and Vision-Language Models (VLMs), enabling agents to interpret and interact with complex environments. Team members refine these models using advanced training approaches, including reinforcement learning and reward modeling. The focus is on better instruction following, tool use, and dynamic interaction. The team’s work bridges research and product, turning new research into practical solutions that move AI forward. Who Hires Here H seeks exceptional AI researchers and engineers from around the world who care about advancing technology safely and responsibly. The company welcomes those eager to shape the future of superintelligent AI alongside a collaborative and driven team.

About ApturaAptura is at the forefront of building reliable AI systems through expertly crafted evaluation datasets and reinforcement learning environments. Our mission is to create robust training data and verifiable task environments in high-stakes industries such as finance, healthcare, and legal. We are a dynamic, small team based in London, dedicated to making significant contributions and innovating quickly. Each team member plays a pivotal role, and we value initiative and ownership. If you're passionate about shaping the future of AI in real-world applications, we want to hear from you.About the RoleAs a Member of the Technical Staff within our Software Engineering team, you will develop the platform that supports Aptura’s operations and scalability. Your responsibilities will encompass the creation of annotation tools, workflow systems, quality control pipelines, and the internal infrastructure that underpins every dataset and environment we produce.Your daily tasks will include designing expert task creation flows, developing task assignment and review interfaces, constructing data pipelines to convert expert outputs into structured training datasets, and integrating LLM-powered tools directly into our product. Your work will span product engineering and infrastructure, ensuring that the software you develop enables our small team to deliver high-quality evaluation data at scale.You will be instrumental in bringing our platform vision to life, determining what features to build and how to build them, while establishing our development standards as we expand.What You'll DoTake ownership of the core data annotation and workflow platform from task assignment to dataset delivery.Create systems that facilitate expert onboarding, task routing, review workflows, and quality assurance at scale.Enhance AI-integrated pipelines across the platform, including LLM-assisted annotation and automated checks.Collaborate directly with founders and domain experts to transform manual processes into scalable software solutions.Make informed product and engineering decisions in fast-paced, ambiguous environments, prioritizing effectively and shipping products without waiting for perfect specifications.Contribute to defining our team’s approach to development, including tooling, engineering practices, and product strategy.Who We're Looking ForWe seek a proactive individual who excels in ambiguous environments and thrives on the challenge of defining projects without strict specifications. If you enjoy problem-solving and have a strong foundation in software engineering, you will fit well within our team.

About UsAt Cohere, we are on a mission to expand intelligence in a way that benefits humanity. We specialize in training and deploying advanced models for developers and enterprises aiming to create AI systems that deliver extraordinary experiences, including content generation, semantic search, retrieval-augmented generation (RAG), and intelligent agents. We are committed to fostering the widespread adoption of AI technology.We take immense pride in what we create. Each team member plays a vital role in enhancing the capabilities of our models and the value they provide to our customers. We thrive in a fast-paced environment where hard work and customer-centricity lead our decisions.Cohere comprises a dynamic group of researchers, engineers, designers, and creatives who are passionate about their work. Our team members are among the best in their fields, and we believe that diverse perspectives are essential for crafting exceptional products.Join us in shaping the future of AI!Why This Role is ExcitingAs a Member of Technical Staff at Cohere, you will be pivotal in defining and developing the future of AI-driven products. This role provides you with the opportunity to convert groundbreaking research into high-performance products that propel our enterprise forward. You will work directly on North, our comprehensive and secure AI workspace platform, focusing on agent development in RAG, tool utilization, and language agents.We boast one of the highest compute-to-engineer ratios globally, offering an environment where your ideas can thrive and be swiftly brought to market.Please note: We have offices in London, Paris, Toronto, San Francisco, and New York. However, we also support remote work within EMEA-friendly time zones. Our team primarily operates between ET and CET, so we are looking for candidates in locations that align with these hours for effective collaboration.As a Member of Technical Staff, your responsibilities will include:Collaborating with a diverse team of engineers to design, build, and scale AI systems that form the backbone of our suite of developer-centric enterprise products.Contributing directly to North, our all-in-one secure AI workspace platform, where you will lead agent development in RAG, tool usage, and language agents.Rapidly researching and experimenting with innovative ideas on our advanced supercomputer and data infrastructure to keep our products at the cutting edge of the industry.Partnering with leading researchers, engineers, and annotators to generate and evaluate data for post-training large language models (LLMs), ensuring our products are top-notch.

About MentisAt Mentis, we are dedicated to creating reliable AI solutions for critical sectors such as finance, healthcare, and legal. Our team specializes in developing meticulously curated evaluation datasets and reinforcement learning environments. We empower AI labs and startups by providing them with expertly crafted training data, calibrated assessment rubrics, and rigorous task environments to push the boundaries of AI capabilities in regulated industries.As a tight-knit team based in London, we pride ourselves on our agility and commitment to excellence. Every member plays a vital role in our mission, and we value initiative and ownership in our collaborative work culture. If you are passionate about shaping the future of frontier AI applications, we want to hear from you.About the RoleAs a Software Engineer and Member of Technical Staff, you will be instrumental in building and scaling the platform that drives Mentis' operations. You will develop essential annotation tools, workflow systems, quality control pipelines, and internal infrastructure fundamental to every dataset and environment we deliver.Your daily tasks will include designing expert task creation workflows, creating task assignment and review interfaces, developing data pipelines to convert expert outputs into structured training sets, and integrating LLM-powered tools into our product. Your role will vary from product engineering to infrastructure development, with a consistent focus on producing high-quality evaluation data at scale.You will take ownership of the platform's development, making key decisions on what features to build, how to implement them, and establishing the standards for our growth.What You'll DoDevelop and manage the core data annotation and workflow platform from start to finish, overseeing task assignment, expert interfaces, quality control, and dataset delivery.Design systems that facilitate expert onboarding, task routing, review workflows, and scalable quality assurance processes.Enhance AI-integrated pipelines across the platform, including LLM-assisted annotation, automated checks, and model-in-the-loop workflows.Collaborate directly with founders and domain experts to streamline bespoke processes into effective, scalable software solutions.Make informed product and engineering decisions in a dynamic environment, prioritizing and shipping features without waiting for perfect specifications.Contribute to defining our team’s development practices, including tooling choices, engineering standards, and product strategy.Who We're Looking ForWe seek a proactive individual who thrives in fast-paced environments and embraces ambiguity. If you are excited about the opportunity to influence how AI learns and operates in real-world settings, we welcome your application.

Join OpenCoreOS as a Systems Engineer!At OpenCoreOS, we redefine banking technology with our innovative, hyper-performant ledger solutions. Utilizing cutting-edge programming languages like Go and Rust, along with multi-region distributed databases, we empower financial institutions to build on a robust, open foundation instead of a cumbersome monolithic structure.Why Choose Us?Designed for AI: AI isn't just an add-on; it's integrated into our operations, enhancing autonomous workflows and creating intelligent, self-healing systems.Unyielding Reliability: We aim for five-nines reliability to ensure our platform can handle the scale of Tier-1 banks, managing millions of daily transactions without compromising consistency.Industry Expertise: Our leadership team merges strategic insights from seasoned banking professionals with practical experience, ensuring we understand the market dynamics we are transforming.Your Role:Core Financial Systems: Develop mission-critical services ensuring accurate value recording and transfer.Transaction Processing: Create reliable transaction flows that maintain integrity during retries and partial failures.Performance Optimization: Profile and enhance key pathways to ensure predictable latency and scalable throughput.Reliability & Observability: Advance metrics, tracing, logging, and incident readiness for our production systems.AI-Enhanced Development: Utilize and refine AI-driven workflows for improved debugging, operations, and developer efficiency.Core Responsibilities:Manage production systems from start to finish.Enforce safety and correctness through rigorous testing and change management.Troubleshoot distributed and system-level challenges (concurrency, performance, data consistency).

About OpenCoreOSA High-Performance Ledger: We deliver an ultra-efficient ledger built on Go, Rust, and multi-region distributed databases, providing banks with a robust, adaptable, and open framework for development, rather than a restrictive monolithic structure.AI-Integrated Solutions: AI is not merely an enhancement; it's an integral aspect of our system architecture. We leverage AI to facilitate autonomous operations, create dynamic development workflows, and establish a self-optimizing platform.Reliability and Openness: Our focus is on achieving five-nines reliability and unwavering consistency, designed to support Tier-1 banks that handle hundreds of millions of transactions daily. By utilizing open technologies and forging new standards, we promote innovation without imposing lock-in constraints.Leadership with Proven Expertise: Our leadership team merges the strategic vision of former McKinsey banking, product, and engineering specialists with the real-world experience of a founder who developed and scaled a mission-critical fintech solution for the world's largest banks. This is complemented by insights from ex-global bank CIOs, providing us with an unmatched understanding of the evolving market landscape.Your RoleLedger Engine: Develop a deterministic, event-sourced transaction engine.Interest & Pricing Engine: Perform high-precision financial calculations.Reconciliation Engine: Ensure invariants, controls, and cross-ledger consistency.Operational Data Store (ODS): Manage a real-time operational data plane.Scalability Layer: Address concurrency, throughput, partitioning, and replication challenges.AI-Driven Development Experience: Work with MCP servers, agent workflows, and automated runbooks.Your Key ResponsibilitiesCreate initial MVPs for Tier-1 banks.Design distributed systems leveraging Go, Kafka, and distributed SQL databases.Manage systems throughout the entire SDLC (coding, testing, DevOps, infrastructure, product development).Implement advanced CI/CD practices and testing automation.

Tessl is an innovative Series A startup headquartered in London, founded by the visionary Guy Podjarny. With over $100M raised from esteemed investors such as Index Ventures, Accel, GV, and Boldstart, we have been recognized among the top players in the industry, ranking #2 in Sifted EU’s B2B SaaS Rising 100 and #20 in Sifted's AI 100 this year.At Tessl, we are on a mission to redefine software development through the power of AI. Our AI Native Developers are pioneering a new approach, defining features, architecture, and workflows through specifications rather than code, effectively guiding the work of AI agents. We are at the forefront of creating a groundbreaking platform that embodies this transformative vision, leading a developer movement and ecosystem.Joining Tessl means becoming an integral part of an early-stage team where you have the chance to influence the future of software creation and maintenance.

Who are we?At Cohere, we are committed to harnessing intelligence to benefit humanity. Our mission focuses on training and deploying advanced models for developers and enterprises, empowering the creation of innovative AI systems that drive exceptional experiences in areas like content generation, semantic search, retrieval-augmented generation (RAG), and intelligent agents. We believe our contributions are vital for the widespread integration of AI technologies.We take immense pride in our creations. Each team member is empowered to enhance the capabilities of our models and the value they deliver to our clients. We thrive in a fast-paced environment and prioritize actions that best serve our customers.Cohere comprises a talented team of researchers, engineers, designers, and other specialists who are dedicated to their craft. Our diverse perspectives are crucial for developing exceptional products.Join us in shaping the future of AI!Why is this role important?In this position, you will push the boundaries of model post-training, deploying state-of-the-art models into production while bridging the divide between research and real-world application. With one of the highest compute-to-engineer ratios globally, we foster collaboration between engineering and research, allowing everyone to contribute to production code and support research initiatives based on their interests and organizational needs. You will have access to the resources you need to excel.Please note: We have offices in London, Paris, Toronto, San Francisco, and New York, but we also support a remote-friendly work culture!As a Technical Staff Member, your responsibilities will include:Developing and implementing high-performance, scalable software for model training.Consistently performing post-training of models to achieve state-of-the-art performance.Collaborating with specialized teams (Agentic, Code, etc.) to create models with comprehensive performance metrics.Designing and executing strategies to enhance performance and outcomes during training cycles, including supervised fine-tuning (SFT) and reinforcement learning (RL).Conducting research and experimentation using our advanced supercomputing and data infrastructures.Learning from and collaborating with leading researchers in the AI field.Ideal candidates will possess:Exceptional software engineering capabilities.A strong understanding of machine learning frameworks and tools.Experience in collaborative development and version control systems.A passion for continuous learning and applying innovative solutions.

About MentisAt Mentis, we specialize in developing evaluation datasets and reinforcement learning environments that ensure AI reliability in high-stakes sectors such as finance, healthcare, and legal. Our dedicated team curates expert training data, establishes precise rubrics, and creates verifiable task environments for AI laboratories and startups that aim to push the boundaries of model capabilities within regulated industries.As a dynamic, close-knit team based in London, we pride ourselves on our ability to adapt quickly and tackle challenges with seriousness. Every team member plays a direct role in our projects, and we value initiative and ownership as key components of our work culture. If you're interested in influencing how cutting-edge AI learns to function in real-world scenarios, we would love to hear from you.About the RoleAs a Member of the Technical Staff within our Applied AI team, your primary focus will be on creating the tasks and environments utilized by AI labs to train and assess their agents across finance, healthcare, and legal domains.Your daily responsibilities will include: designing reinforcement learning environments around documents, spreadsheets, and professional workflows; developing verification logic and reward functions; collaborating with domain experts to define what constitutes a correct response in various scenarios, such as an LBO model or clinical notes. This role will involve both engineering and research activities, with the common goal of producing the ground truth against which advanced models are evaluated.What You'll DoDevelop reinforcement learning environments across finance, healthcare, and legal sectors.Contribute to the design of tasks featuring definitive answers, calibrated rubrics, and programmatic reward signals.Implement verification logic and reward functions to differentiate between effective and ineffective model outputs.Engage directly with domain experts (investment analysts, physicians, attorneys) to convert intricate professional workflows into structured tasks.Innovate new methods for evaluation, verification, and synthetic data creation.Who We're Looking ForHands-on experience with large language models (LLMs), including prompting, evaluation, and agent integration. You’ve developed systems that function effectively, not just theoretical models.Demonstrated initiative and technical proficiency. You proactively identify needs, determine solutions, and execute them without waiting for directives.Adaptability to work in diverse contexts. Your role will frequently involve shifting between engineering, evaluation design, and collaborative work with domain experts.A commitment to delivering and refining outputs. In our small team, we prioritize action over prolonged review processes.

Join Wintermute as an Infrastructure Support EngineerAt Wintermute, a leading technology unicorn and one of the largest algorithmic trading firms specializing in digital assets, we are on the lookout for passionate individuals to join our infrastructure team. We provide liquidity across various cryptocurrency exchanges, offer a range of OTC trading solutions, and support esteemed blockchain projects and traditional financial institutions transitioning into the crypto realm. Additionally, our Wintermute Ventures arm invests in promising early-stage DeFi projects.Founded in 2017, Wintermute has successfully navigated through various industry cycles. Our culture merges the rigorous technology standards of high-frequency trading firms with the innovative spirit of technology startups. We are committed to harnessing the potential of blockchain technology and taking a leadership role in building a compliant and innovative digital asset market.Role OverviewAs an Infrastructure Support Engineer, you will play a crucial role within our systems administration group. This primarily technical support position focuses on our mixed environment, integrating both physical and virtual computing resources. Your responsibilities will include providing technical support for our automated desktop setup.We seek responsible and enthusiastic candidates eager to launch or advance their careers in infrastructure. This position offers the chance to collaborate with and learn from our senior technologists, enhancing your automation skills, particularly in Python. As our business evolves, your role will be vital in maintaining our networks and computing environments.Wintermute is dedicated to fostering the growth of your automation capabilities.

Join Our TeamLatent Labs is on the lookout for a talented Machine Learning Research Engineer with extensive expertise in training and deploying large-scale generative models. In this pivotal role, you will oversee our high-performance computing infrastructure and drive our model serving initiatives. You will collaborate with a diverse team of machine learning experts, protein engineers, and biologists, all dedicated to transforming how we manipulate biological systems and develop innovative treatments for diseases.About Latent LabsAt Latent Labs, we are pioneers in creating advanced models that grasp the core principles of biology. Our team, which once co-developed DeepMind's groundbreaking AlphaFold and invented latent diffusion, is committed to scientific rigor and ambitious exploration. By joining us, you will work alongside some of the most brilliant minds in the fields of generative AI and biology, fostering a culture of collaboration and continuous learning between our London and San Francisco offices.We seek innovators who are passionate about solving complex problems and making a positive impact on the world. Be a part of our ambitious mission!

Join Perplexity, a pioneering company based in London, as we transform the way users search and engage with the internet. We are seeking seasoned Infrastructure Engineers to become integral members of our dynamic team. In this role, you will lead the design, implementation, and scaling of innovative tools, systems, and platforms that empower web, mobile, and browser engineers to develop cutting-edge products. Your contributions will be vital in enabling our product, AI, and development teams to innovate swiftly while ensuring utmost reliability, security, and performance at scale.Our Tech StackPython | Go | TypeScript | PostgreSQL | DynamoDB | Redis | FastAPI | React | Bazel | GitHub | AWSTeams HiringSenior/Staff PlatformThe Platform team is fundamental to ensuring product reliability, scalability, and performance at Perplexity. This elite team is responsible for developing and maintaining the critical infrastructure—from backend systems such as authentication, real-time data flows, and service orchestration to frontend frameworks that guarantee fast, reliable, and secure user experiences. By upholding stringent standards for code quality, uptime, and developer productivity, the Platform team enables all of Perplexity to innovate rapidly on a solid, well-designed foundation.Senior/Staff DevXThe Developer Experience (DevX) team is dedicated to empowering engineers at Perplexity to build, ship, and iterate faster than ever before. They manage internal platforms for source control, build, test, and deployment, effectively removing bottlenecks from each phase of product development. This team designs seamless onboarding, ultra-fast CI/CD pipelines, and developer tools that enhance creativity and safety at scale. Through collaborative efforts and significant autonomy, the DevX team amplifies the contributions of every engineer, facilitating rapid, dependable innovation across the organization.Senior/Staff Cloud InfraThe Cloud Infrastructure team architects and manages the essential cloud infrastructure that powers Perplexity’s global platform. This team designs and scales computing, storage, and networking systems to support high-throughput, low-latency workloads, balancing proactive project initiatives with operational support. Collaboration with product, AI research, security, and other teams ensures that our services remain consistently available, reliable, and responsive to user demands.

POS-22139This position offers flexible work options: Office, Hybrid, or Remote within the UKAt HubSpot, we are dedicated to equipping businesses with state-of-the-art AI technologies, and our AI Infrastructure group plays a pivotal role in this mission. We are looking for a Staff Software Engineer who is passionate about infrastructure and improving the developer experience to join our dynamic AI Serving team. This team is responsible for managing HubSpot's end-to-end model inference and serving infrastructure, ensuring that AI models are deployed reliably, scaled appropriately, and remain cost-effective across various environments, while also serving as the cornerstone for modern Python development at HubSpot.The AI Serving team is in charge of the frameworks and libraries that facilitate synchronous, asynchronous, and offline inference, including model deployment pipelines, autoscaling, and resource management for both GPU and CPU. Our roadmap is focused on enhancing batch inference reliability and efficiency, advancing model observability, and optimizing AI infrastructure costs. Additionally, we are the custodians of essential Python libraries and tools within HubSpot.As a Staff Software Engineer on the AI Serving team, your responsibilities will include:Developing and deploying production-level code that directly enhances AI capabilities across HubSpot, serving as a crucial component for user and business impact at scale.Driving the advancement of our model serving and inference infrastructure, with an emphasis on reliability, scalability, and cost efficiency.Setting the technical direction for deploying and operating ML models at scale, influencing decisions on architecture, cost management, and developer experience.Collaborating closely with Machine Learning Engineers, Product Software Engineers, and other Infrastructure teams to streamline model deployment and serving processes.Gaining in-depth exposure to a variety of HubSpot infrastructure systems by building and maintaining core Python libraries, providing an excellent opportunity to understand HubSpot's operations in detail.Engaging with HubSpotters across the organization—from engineering and product to design, research, marketing, and sales—to gain insights into how HubSpot functions as a business.Being encouraged to bring your authentic self to work and to choose a work style and location that enables you to perform at your best, whether that be from home, in an office, or a combination of both.We are not solely seeking engineers with extensive experience; we are looking for individuals who have demonstrated unique excellence, leadership qualities, and the ability to uplift those around them.

Technical Staff Member - Applied AIExciting Opportunity Awaiting YouWe are seeking a talented Member of Technical Staff specializing in generative modeling to bridge the gap between our cutting-edge models and the clients who rely on them. You will be a part of a diverse team comprising machine learning experts, protein engineers, and biologists, all collaboratively working to revolutionize biological control and disease treatment. In this role, you will gain a thorough understanding of our proprietary generative models and leverage that expertise to adapt, deploy, and optimize these models in client environments, especially within the pharmaceutical and biotech industries.This is a hybrid position requiring a research-oriented mindset coupled with excellent communication skills to effectively translate complex concepts into practical production systems that yield scientific benefits for our partners.About Latent LabsAt Latent Labs, we are committed to developing pioneering models that grasp the fundamentals of biology. Our ambitious goals are driven by curiosity and an unwavering commitment to scientific excellence. Our team previously contributed to the award-winning AlphaFold project at DeepMind, invented latent diffusion, and established groundbreaking lab data management and high-throughput protein screening systems. At Latent Labs, you'll collaborate with some of the brightest minds in generative AI and biology.We foster an environment of interdisciplinary exchange, continuous learning, and collaboration. Our offsite team-building activities promote a culture of trust across our London and San Francisco offices.We are looking for innovative thinkers who are passionate about solving complex challenges and making a positive global impact. Join us on our ambitious mission!

About H H is focused on advancing superintelligence by developing agentic AI. The team’s mission is to automate complex, multi-step tasks that typically require human effort, enabling AI agents to extend what people can achieve. H values open collaboration, continuous learning, and responsible progress. The company seeks people who care deeply about building agentic technologies safely and who want to contribute to a culture where every voice matters. About the Agent Team The Agent team shapes new learning algorithms and agent paradigms that move agentic systems forward. Work centers on foundational models and reinforcement learning, with a focus on training artificial general agents. Collaboration with the LLM/VLM and Safety teams is central, as the group explores new research directions together. Role Overview: Technical Staff Member - Research - Agent This position is part of the research team and centers on engineering. The main responsibility: define system architectures and build scalable platforms that underpin research efforts. The work involves turning research ideas into reliable, high-performance systems ready for production, supporting the next wave of agentic AI. Location London