Research Engineer / Research Scientist, Post-Training

About the TeamJoin the innovative Post-Training team at OpenAI, where we focus on refining and elevating pre-trained models for deployment in ChatGPT, our API, and future products. Collaborating closely with various research and product teams, we conduct crucial research that prepares our models for real-world deployment to millions of users, ensuring they are safe, efficient, and reliable.About the RoleAs a Research Engineer / Scientist, you will spearhead the research and development of enhancements to our models. Our work intersects reinforcement learning and product development, aiming to create cutting-edge solutions.We seek passionate individuals with robust machine learning engineering skills and research experience, particularly with innovative and powerful models. The ideal candidate will be driven by a commitment to product-oriented research.This position is located in San Francisco, CA, and follows a hybrid work model requiring three days in the office each week. Relocation assistance is available for new employees.In this role, you will:Lead and execute a research agenda aimed at enhancing model capabilities and performance.Work collaboratively with research and product teams to empower customers to optimize their models.Develop robust evaluation frameworks to monitor and assess modeling advancements.Design, implement, test, and debug code across our research stack.You may excel in this role if you:Possess a deep understanding of machine learning and its applications.Have experience with relevant models and methodologies for evaluating model improvements.Are adept at navigating large ML codebases for debugging purposes.Thrive in a fast-paced and technically intricate environment.About OpenAIOpenAI is a pioneering AI research and deployment organization dedicated to ensuring that general-purpose artificial intelligence benefits all of humanity. We are committed to pushing the boundaries of AI capabilities while prioritizing safety and human-centric values in our products. Our mission is to embrace diverse perspectives, voices, and experiences that represent the full spectrum of humanity, as we strive for a future where AI is a powerful ally for everyone.

About Our TeamJoin the forefront of AI innovation with the RL and Reasoning team at OpenAI. Our team is dedicated to advancing reinforcement learning research and has pioneered transformative projects, including o1 and o3. We are committed to pushing the limits of generative models while ensuring their scalable deployment.About the RoleAs a Research Engineer/Research Scientist at OpenAI, you will play a pivotal role in enhancing AI alignment and capabilities through state-of-the-art reinforcement learning techniques. Your contributions will be essential in training intelligent, aligned, and versatile agents that power various AI models.We seek individuals with a solid foundation in reinforcement learning research, agile coding skills, and a passion for rapid iteration.This position is located in San Francisco, CA, and follows a hybrid work model of three days in the office per week. We also provide relocation assistance for new hires.You may excel in this role if:You are enthusiastic about being at the cutting edge of RL and language model research.You take initiative, owning ideas and driving them to fruition.You value principled methodologies, conducting simple experiments in controlled environments to draw trustworthy conclusions.You thrive in a fast-paced, complex technical environment where rapid iteration is essential.You are adept at navigating extensive ML codebases to troubleshoot and enhance them.You possess a profound understanding of machine learning and its applications.About OpenAIOpenAI is a pioneering AI research and deployment organization committed to ensuring that general-purpose artificial intelligence serves the greater good for humanity. We strive to push the boundaries of AI system capabilities while prioritizing safe deployment through our innovative products. We recognize AI as a powerful tool that must be developed with safety and human-centric principles, embracing diverse perspectives to reflect the full spectrum of humanity.We are proud to be an equal opportunity employer, welcoming applicants from all backgrounds without discrimination based on race, religion, color, national origin, sex, sexual orientation, age, veteran status, disability, genetic information, or any other legally protected characteristic.

Innovating Self-Improving SuperintelligenceAt Letta, we are on a transformative journey to enhance artificial intelligence to be as adaptive and capable of learning as the human brain. Our mission is to create self-improving AI agents that continuously learn from their experiences and evolve over time.Founded by the visionary team behind MemGPT at UC Berkeley’s Sky Computing Lab—the birthplace of Spark and Ray—we are supported by industry leaders like Jeff Dean and Clem Delangue. Our cutting-edge agents are already in action at leading companies such as 11x and Bilt Rewards, improving their operations daily.Join our elite team of researchers and engineers as we tackle one of AI's greatest challenges: developing machines that can think, remember, and learn in ways similar to humans.This position is in-person (no hybrid), requiring presence 5 days a week at our downtown San Francisco office.

About Retell AI Retell AI develops advanced voice AI technology for call centers, using first-principles approaches to create intelligent voice agents. These agents help businesses manage sales, support, and logistics communications while reducing reliance on large human teams. The company has reached $36M ARR in just 18 months, backed by Y Combinator and Alt Capital. With a team of 20, Retell AI is building a comprehensive customer experience platform, aiming for AI-powered contact centers by 2026. The vision: intelligent agents that execute, monitor, and improve customer interactions with minimal human oversight. Named a top 50 AI app by a16z: https://tinyurl.com/5853dt2x Ranked #4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025 Featured among top startups: https://leanaileaderboard.com/ Role Overview: Research Scientist - Voice AI Innovation This role centers on advancing machine learning for human-like voice agents in real-world settings. The Research Scientist will explore new methods in large language models (LLMs) and audio models, design evaluation techniques, and prototype systems that improve reasoning, reduce latency, and enhance conversational quality. The work involves open-ended ML challenges, rapid experimentation, and direct influence on the performance and cognitive abilities of voice AI systems at scale. Location San Francisco Bay Area

About GranicaGranica is an innovative AI research and infrastructure firm dedicated to creating reliable, steerable representations of enterprise data.We establish trust through Crunch, a policy-driven health layer optimizing large tabular datasets for efficiency, reliability, and reversibility. Utilizing this foundation, we are developing Large Tabular Models—systems designed to learn cross-column and relational structures, delivering trustworthy answers and automation with integrated provenance and governance.Our MissionCurrent AI capabilities are hindered not only by model design but also by the inefficiencies of the data that supports it. At scale, each redundant byte, poorly organized dataset, and inefficient data pathway contributes to significant costs, latency, and energy waste.Granica’s mission is to eliminate these inefficiencies. We leverage groundbreaking research in information theory, probabilistic modeling, and distributed systems to craft self-optimizing data infrastructure: systems that continually enhance how information is represented and utilized by AI.Led by Prof. Andrea Montanari from Stanford, Granica’s Research group merges advances in information theory with learning efficiency in large-scale distributed systems. We collectively believe that the next significant leap in AI will originate from innovations in efficient systems, rather than merely larger models.Granica is at the forefront of developing a new category of structured AI models: foundational models designed to learn and reason from the relational, tabular, and structured data that drives the global economy. While many focus on unstructured text or media, we are venturing into the next frontier: systems capable of comprehending and reasoning over structured information.Your ContributionsCreate and prototype algorithms that form the core of structured AI, enhancing representation learning and efficient information modeling for enterprise and tabular data at petabyte scale.Develop adaptive learners merging statistical learning theory with systems optimization at scale, contributing to a new generation of foundational models for structured information.Design architectures that unify symbolic, relational, and neural components, enabling AI systems to reason directly over structured enterprise data.Construct cost models and optimization frameworks that enhance the efficiency of structured learning, both computationally and economically.

AI Research ScientistAt Substrate, we are tackling a critical technological challenge that impacts the United States. Positioned at the crossroads of advanced manufacturing and innovative physics, our mission is to develop transformative technologies that will revolutionize the semiconductor industry and bolster America's technological dominance. Our team comprises top-tier scientists, engineers, and technical specialists dedicated to pushing the boundaries of technology for the benefit of the nation.As an AI Research Scientist, you will play a key role in enhancing and accelerating research and development processes by harnessing machine learning techniques for scientific simulations and modeling. You will also focus on establishing internal AI capabilities throughout our organization. This position merges cutting-edge physics with artificial intelligence, requiring hands-on development of AI-enhanced tools that facilitate groundbreaking research. You will also contribute to building the infrastructure and expertise required for our technical teams to effectively use AI in their workflows. Whether you are a physicist who has adopted machine learning or an AI expert with a solid scientific background, you will be instrumental in shaping our approach to utilizing AI to expedite our internal R&D efforts.

AI Research ScientistOverviewJoin Physical Superintelligence, an innovative startup rooted in prestigious institutions such as Harvard, MIT, Johns Hopkins, Oxford, the Institute for Advanced Study, and the Perimeter Institute. We are at the forefront of building AI systems designed to uncover groundbreaking insights in physics on a grand scale. We are in search of talented AI researchers dedicated to developing reinforcement learning agents and training frameworks that propel scientific discovery.Key Responsibilities- Develop and optimize AI systems aimed at physics discovery, collaborating with physicists on verification harnesses and engineers on training infrastructure.- Address critical AI research questions related to agent learning in physics reasoning, action space design for scientific exploration, reward structure development, and scalable training systems.- Construct and train reinforcement learning agents leveraging cutting-edge methodologies such as PPO, SAC, MuZero, and multi-agent self-play.- Design agent architectures tailored for physics reasoning and scientific tool utilization.- Execute training curricula and reward structures for discovery tasks.- Establish evaluation workflows and benchmarks to assess physics reasoning capabilities.- Develop instrumentation to analyze agent behavior and learning dynamics.- Collaborate closely with physicists and engineers to refine system design and architecture.Candidate ProfileWe are looking for candidates with a strong background in developing agents and training models using reinforcement learning. Proficiency in modern machine learning frameworks and experience with distributed training systems is essential, alongside a proven track record of deploying effective AI systems.Essential Skills:- Practical experience with contemporary reinforcement learning algorithms including PPO, SAC, MuZero, and multi-agent self-play.- Proficient in PyTorch or JAX, with hands-on experience in distributed training using Ray, XLA, or Accelerate, and familiarity with modern pretraining workflows.Preferred Background:- A strong foundation in physics or mathematics that enhances intuition for physical reasoning and mathematical modeling.- Experience applying agents in simulators, games, scientific tool use, or benchmark design employing rigorous experimental methodologies.

About Our TeamJoin the Foundations Research team, where we tackle ambitious and innovative projects that could redefine the future of AI. Our mission is to enhance the science behind our training and scaling initiatives, focusing on pioneering frontier models. We are dedicated to advancing data utilization, scaling methodologies, optimization strategies, model architectures, and efficiency enhancements to accelerate our scientific breakthroughs.About the PositionWe are on the lookout for a dynamic technical research lead to spearhead our embeddings-focused retrieval initiatives. You will oversee a talented team of research scientists and engineers committed to developing foundational technologies that enable models to access and utilize the right information precisely when needed. This includes crafting innovative embedding training objectives, architecting scalable vector storage, and implementing adaptive indexing techniques.This pivotal role will contribute to various OpenAI products and internal research initiatives, offering opportunities for scientific publication and significant technical influence.This position is located in San Francisco, CA, where we embrace a hybrid work model, requiring three days in the office weekly, and we provide relocation assistance for new hires.Your ResponsibilitiesLead cutting-edge research on embedding models and retrieval systems optimized for grounding, relevance, and adaptive reasoning.Supervise a team of researchers and engineers in building an end-to-end infrastructure for training, evaluating, and integrating embeddings into advanced models.Drive advancements in dense, sparse, and hybrid representation techniques, metric learning, and retrieval systems.Work collaboratively with Pretraining, Inference, and other Research teams to seamlessly integrate retrieval throughout the model lifecycle.Contribute to OpenAI's ambitious vision of developing AI systems with robust memory and knowledge access capabilities rooted in learned representations.You Will Excel in This Role If You PossessA proven track record of leading high-performance teams of researchers or engineers within ML infrastructure or foundational research.In-depth technical knowledge in representation learning, embedding models, or vector retrieval systems.Familiarity with transformer-based large language models and their interaction with embedding spaces and objectives.Research experience in areas such as contrastive learning and retrieval-augmented generation.

Join Perplexity in our mission to redefine the future of AI-powered search and agent experiences! We are on the lookout for exceptional AI Research Scientists and Engineers who are eager to push the boundaries of technology. Our innovative products, including Sonar models, Deep Research Agent, Comet Agent, and advanced search tools, are designed to handle hundreds of millions of queries and are scaling rapidly. If you have a passion for cutting-edge AI and want to contribute to state-of-the-art experiences, we would love to hear from you!Team StructureDepending on your interests and expertise, you will have the opportunity to collaborate within one of three specialized teams:1. Core Research TeamThis team focuses on the generation and enhancement of foundational models that underpin all our products, emphasizing core model capabilities and the development of infrastructure that serves the entire organization.2. Agent Products TeamThis team specializes in fine-tuning and optimizing models specifically for our Deep Research Agent and Labs/Canvas products, ensuring that our agent functionalities provide exceptional user experiences.3. Comet Agent TeamDedicated to the development and refinement of the Comet Agent product, this team addresses the unique requirements and optimizations necessary for Comet's specific use cases.ResponsibilitiesResearch & DevelopmentPost-train state-of-the-art large language models (LLMs) using cutting-edge supervised and reinforcement learning methodologies (SFT/DPO/GRPO).Utilize our comprehensive query-answer dataset to scale model performance across our Sonar, Deep Research, Comet, and Search products.Remain abreast of the latest advancements in LLM research, focusing on model training, optimization, and personalization techniques.Implement preference optimization and personalization features to elevate user experience.Innovate and develop in-house enhancements and optimizations for state-of-the-art models.Translate research ideas into algorithms and conduct experiments to deploy new models.Infrastructure & ImplementationOversee the full-stack data, training, and evaluation pipelines that are essential for model development.Create robust and efficient training frameworks (based on Megatron/PyTorch) for post-training LLMs.Establish necessary infrastructure components to support cutting-edge model development.

About Retell AI Retell AI builds voice AI technology that helps businesses transform their call center operations. In just 18 months, thousands of companies have adopted Retell’s AI voice agents to streamline sales, support, and logistics, work that once required large human teams. Backed by investors including Y Combinator and Alt Capital, Retell has grown annual recurring revenue from $5M to $36M with a focused team of 20. The company’s goal for 2026: a modern customer experience platform where AI powers entire contact centers. Retell is developing AI “workers” that can serve as frontline agents, quality assurance analysts, and managers, handling, evaluating, and improving customer interactions on their own. Named a top 50 AI app by a16z: https://tinyurl.com/5853dt2x Ranked #4 on Brex’s Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025 Featured on the Lean AI Leaderboard: https://leanaileaderboard.com/ Role Overview: Research Scientist – LLM Retell AI is hiring a Research Scientist focused on large language models (LLMs) and audio processing. This role suits machine learning researchers who want to push the boundaries of real-time AI and see their work in production. What You Will Do Investigate new approaches in large language models and audio processing for human-like voice agents Design and implement evaluation methods for complex, real-world conversational systems Prototype systems to improve reasoning, reduce latency, and enhance conversation quality Work closely with engineering and product teams to bring research advances into production Impact Research at Retell directly shapes the capabilities of voice AI agents for thousands of businesses. The work blends advanced research with practical deployment, improving how customers interact with automated systems across industries. Location This position is based in the San Francisco Bay Area.

Join the Center for AI Safety (CAIS), a premier research and advocacy organization dedicated to addressing the complex societal challenges posed by artificial intelligence (AI). Our mission focuses on mitigating large-scale risks associated with AI through groundbreaking technical research, strategic initiatives, and proactive policy engagement, in collaboration with our sister organization, the Center for AI Safety Action Fund. As a Senior Research Scientist at CAIS, you will spearhead and execute transformative research aimed at enhancing the safety and reliability of advanced AI systems. You will take ownership of significant open challenges, driving them to successful publication. We seek individuals who set a high standard for research excellence and contribute innovative ideas to elevate our collective understanding. Your role will involve designing and conducting experiments on large language models, developing the necessary tools for large-scale model training and evaluation, and translating findings into publishable research. Close collaboration with CAIS researchers and external academic and industry partners will be essential, utilizing our compute cluster for extensive training and evaluation projects. Research areas include AI honesty, robustness, transparency, and mitigating trojan/backdoor behaviors, all geared towards reducing real-world risks from sophisticated AI systems.

Join OpenAI as a Research Scientist and explore cutting-edge machine learning innovations. In this role, you will be at the forefront of developing groundbreaking techniques while advancing our team's research initiatives. Collaborate with talented peers across various teams to discover transformative ideas that scale effectively. We seek individuals who are passionate about pushing the boundaries of AI and want to contribute to our unified research vision.

At Scale AI, we collaborate with leading AI laboratories to supply high-quality data and foster advancements in Generative AI research. We seek innovative Research Scientists and Research Engineers with a strong focus on post-training techniques for Large Language Models (LLMs), including Supervised Fine-Tuning (SFT), Reinforcement Learning from Human Feedback (RLHF), and reward modeling. This position emphasizes optimizing data curation and evaluation processes to boost LLM performance across text and multimodal formats. In this pivotal role, you will pioneer new methods to enhance the alignment and generalization of extensive generative models. You will work closely with fellow researchers and engineers to establish best practices in data-driven AI development. Additionally, you will collaborate with top foundation model labs, providing critical technical and strategic insights for the evolution of next-generation generative AI models.

Join Scale Labs as a Research Scientist – AI Controls and MonitoringScale AI is at the forefront of data solutions for pioneering AI enterprises, playing a crucial role in understanding and protecting AI models and systems. Our new team within Scale Labs is dedicated to policy research, bridging the divide between AI advancements and global policymakers to make informed and scientific decisions regarding AI risks and capabilities.We tackle complex challenges in agent robustness, AI control mechanisms, and risk evaluations, assisting governments, industries, and the public in understanding and mitigating AI risks while fostering AI adoption. Our collaborative efforts involve partnerships across various sectors, including industry, public entities, and academia, and we regularly share our findings with the community. We are looking for passionate researchers to help us fulfill this vision.As a Research Scientist specializing in AI Controls and Monitoring, you will develop methodologies, systems, and experiments to ensure advanced AI models and agents stay aligned with their intended goals, even in critical or adversarial situations. Your responsibilities may include:Creating monitoring strategies and observability techniques to track AI behavior in real-time, identifying and flagging deviations, emergent capabilities, or anomalous outputs;Investigating layered control mechanisms, including fail-safes, oversight protocols, and intervention strategies to redirect AI systems when risks arise;Designing red-team simulations to uncover vulnerabilities in oversight and control frameworks, and implementing measures to address identified gaps;Collaborating with policymakers, engineers, and researchers to establish standards and benchmarks for AI monitoring and escalation.

Join Flexion Robotics as an AI Research Scientist, where you will play a pivotal role in advancing our innovative robotics technology. We are looking for passionate individuals who are eager to push the boundaries of artificial intelligence and robotics. In this role, you will lead research initiatives, develop algorithms, and collaborate with a talented team to create cutting-edge solutions.

At Scale AI, we are at the forefront of artificial intelligence, driving innovation through our advanced data, infrastructure, and tooling that empower the most sophisticated models worldwide. Our teams thrive at the intersection of pioneering research, extensive engineering, and practical deployment, collaborating with leading labs, enterprises, and government entities to explore the vast potential of Generative AI. As AI technology evolves from static models to dynamic, intelligent systems, Scale AI is dedicated to establishing the essential research foundations, evaluation methodologies, and reinforcement learning infrastructure that will shape this transformative era. Join our high-impact research organization, where you will contribute to advancing large language models, post-training evaluation, and agent-based reinforcement learning environments, influencing the future of AI development and implementation. As the Research Scientist Manager, you will spearhead a distinguished team of research scientists and engineers, define the strategic research roadmap, and oversee projects from initial prototyping to final deployment. You will excel in a fast-paced environment, harmonizing deep technical leadership with effective people management, visionary goal setting, and successful delivery.

Join Our Innovative TeamAt OpenAI, our Safety Systems team is at the forefront of ensuring that AI models are safe, robust, and reliable for real-world applications. We are committed to the principle set forth in our charter: to widely distribute the benefits of AI technology. Our Health AI unit is dedicated to providing equitable access to high-quality medical information. By bridging AI safety research with healthcare applications, we strive to develop trustworthy AI systems that empower medical professionals and enhance patient care.The OpportunityWe are on the lookout for passionate researchers who are eager to contribute to AI safety and improve health outcomes globally. As a Health AI Research Scientist, your role will involve developing safe and effective AI models tailored for healthcare applications. You will implement innovative methods to enhance the behavior, knowledge, and reasoning capabilities of our models. This necessitates research into safety and alignment techniques that can be generalized to ensure a beneficial AGI.This position is based in San Francisco, CA, utilizing a hybrid work model (3 days in the office per week) and we provide relocation assistance for new hires.Key Responsibilities:Design and implement scalable methods to enhance the safety and reliability of our models, such as Reinforcement Learning from Human Feedback (RLHF), automated red teaming, and scalable oversight.Assess methodologies using health-related data to ensure models deliver accurate, reliable, and trustworthy information.Develop reusable libraries to apply general alignment techniques across our models.Proactively analyze the safety of our models and systems, identifying potential risk areas.Collaborate with cross-functional teams to embed safety methods into core model training and drive safety improvements in OpenAI products.Ideal Candidate Profile:Align with OpenAI’s mission to ensure AGI benefits everyone and resonate with our charter.Exhibit a strong passion for AI safety and enhancing global health outcomes.Possess 4+ years of experience in AI research, with a focus on health applications.Demonstrate proficiency in machine learning frameworks and safety techniques.Showcase effective communication skills for cross-team collaboration.

About UsAt Latent Labs, we are at the forefront of developing advanced models that delve into the core principles of biology. Our ambitious pursuits are driven by curiosity and a steadfast commitment to scientific excellence. The team behind Latent Labs previously co-developed DeepMind's Nobel Prize-winning AlphaFold, pioneered latent diffusion technology, and created groundbreaking laboratory data management systems alongside high-throughput protein screening platforms. By joining us, you will collaborate with some of the brightest minds in the fields of generative AI and biology.We believe in fostering interdisciplinary collaboration, continuous learning, and teamwork. Our team offsites are designed to cultivate a culture of trust between our London and San Francisco locations.We're on the lookout for innovators who are passionate about solving complex challenges and making a positive global impact. Be part of our monumental mission!Your RoleWe are excited to invite a Research Scientist to join our team, working at the intersection of generative AI and biology. The ideal candidate will have a solid background in molecular biology, biochemistry, mammalian cell culture, and high-throughput screening techniques. You will collaborate with colleagues and work independently to develop and implement screening assays aimed at functionally testing and characterizing novel proteins generated through our proprietary models.This is a unique opportunity to contribute to an organization that advances artificial intelligence in addressing long-standing scientific challenges. A strong technical skill set, adaptability, organizational prowess, and exceptional communication abilities are essential, as is the capability to thrive both independently and as part of a dynamic, collaborative team.

About Scale AI At Scale AI, we are committed to propelling the advancement of AI technologies. For over eight years, we have been a pioneer in the AI data sector, supporting groundbreaking innovations in areas such as generative AI, defense solutions, and autonomous driving. Following our recent Series F funding round, we are enhancing access to premium data to accelerate the journey towards Artificial General Intelligence (AGI). Building on our legacy of model evaluation for both enterprise and governmental clients, we are expanding our capabilities to establish new benchmarks for evaluations in both public and private domains. About This Role This position is at the leading edge of AI research and practical implementation, concentrating on reasoning within large language models (LLMs). The successful candidate will investigate critical data types vital for evolving LLM-based agents, including browser and software engineering agents. You will significantly influence Scale’s data strategy by pinpointing optimal data sources and methodologies to enhance LLM reasoning. To excel in this role, you will require a profound understanding of LLMs, planning algorithms, and fresh approaches to agentic reasoning, alongside inventive solutions to challenges in data generation, model interaction, and evaluation. Your contributions will lead to transformative research on language model reasoning, facilitate collaboration with external researchers, and engage closely with engineering teams to translate cutting-edge advancements into scalable, real-world applications.

Join Canva as a Staff Research Scientist specializing in Video & Audio Generative AI. In this pivotal role, you will leverage your expertise in AI to develop innovative solutions that enhance our platform's multimedia capabilities. Collaborate with cross-functional teams to push the boundaries of AI technology, driving impactful projects that redefine user experiences.