Top AI companies in the United States

Companies building AI products, foundation models, and applied ML platforms. Filtered to companies headquartered in the United States.

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Built from a search like: “Top AI companies in the United States”

Ranked by current headcount across AI companies headquartered in the United States. Refreshed monthly.

1
PPD· Waltham, Massachusetts, United States
The PPDTM clinical research business of Thermo Fisher Scientific, the world leader in serving science, enables customers to accelerate innovation and drug development through patient-centered strategies and data analytics. Our services, which span multiple therapeutic areas, include early development, all phases of clinical development, peri- and post-approval, patient recruitment, investigator sites and comprehensive laboratory services. As a global industry leader, we offer custom solutions to pharma, biotech, medical device, and government organizations, leveraging cutting-edge technology and therapeutic expertise to help customers deliver life-changing therapies.
- Private equity
- 20k employees
- Founded 1985
2
Los Alamos National Laboratory· Los Alamos, New Mexico, United States
Los Alamos National Laboratory is one of the world’s most innovative multidisciplinary research institutions. We're engaged in strategic science on behalf of national security to ensure the safety and reliability of the U.S. nuclear stockpile. Our workforce specializes in a wide range of progressive science, technology and engineering across many exciting fields, including space exploration, geophysics, renewable energy, supercomputing, medicine and nanotechnology.
- Grant
- 13.8k employees
- Founded 1943
3
OpenAI· San Francisco, California, United States
OpenAI is an AI research and deployment company dedicated to ensuring that general-purpose artificial intelligence benefits all of humanity. AI is an extremely powerful tool that must be created with safety and human needs at its core. OpenAI is dedicated to putting that alignment of interests first — ahead of profit.To achieve our mission, we must encompass and value the many different perspectives, voices, and experiences that form the full spectrum of humanity. Our investment in diversity, equity, and inclusion is ongoing, executed through a wide range of initiatives, and championed and supported by leadership.At OpenAI, we believe artificial intelligence has the potential to help people solve immense global challenges, and we want the upside of AI to be widely shared. Join us in shaping the future of technology.
- Series unknown
- 10.7k employees
- Founded 2015
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4
US Department of Agriculture (USDA) Agricultural Research Service (ARS)· Washington, District of Columbia, United States
ARS enjoys deep-historic roots as the principal in-house research agency of the US Department of Agriculture (USDA). Federally-supported agricultural research dates back to the 1862 Organic Act, which established what is now the USDA. The Organic Act charged the then-Commissioner of Agriculture “To acquire and preserve... all information he can obtain by means of books and correspondences, and by practical and scientific experiments...” ARS was founded in 1963 with the vision of leading America towards a better future by fulfilling this charge through agricultural research and information.ARS employs 2000 scientists and post-docs at over 90 locations across the country. Collectively, our scientists are engaged in almost 700 cutting-edge research projects at any given moment. Projects range from how to reduce nitrate runoff on Midwest farms, to best practices for Honey Bee management. The information, technology, and improved techniques originating in the ARS scientific community have profound and wide-ranging impacts on all consumers domestic and abroad.
- 9.9k employees
- Founded 1953
5
Lawrence Livermore National Laboratory· Livermore, California, United States
Lawrence Livermore National Laboratory, located in the San Francisco Bay Area, is a premier applied science laboratory that is part of the National Nuclear Security Administration within the Department of Energy.LLNL's mission is strengthening national security by developing and applying cutting-edge science, technology, and engineering that respond with vision, quality, integrity, and technical excellence to scientific issues of national importance. The Laboratory's science and engineering are being applied to achieve breakthroughs for counterterrorism and nonproliferation, defense and intelligence, energy and environmental security.The world-class programs and capabilities at the Lawrence Livermore National Laboratory span one square mile, what many consider to be "the smartest square mile on Earth."
- Grant
- 9.6k employees

6
MITRE· McLean, Virginia, United States
MITRE is a nonprofit systems engineering, applied research, and advanced technology organization. We’re a leader in federally funded research, delivering deep technical integration, developing rapid prototypes, and innovating in the public interest. We serve as a force multiplier across multiple U.S. government agencies to bring together the right technologies and partners. Addressing complex mission challenges, we strengthen our nation’s security, health, and prosperity.
- Grant
- 9.2k employees
- Founded 1958
7
U.S. Geological Survey (USGS)· Herndon, Virginia, United States
Part of the U.S. Department of the Interior, the USGS began in 1879 to study the nation’s lands and resources. Today, we monitor, analyze, and predict Earth’s changing systems. Our science provides clear, reliable data that protects lives and property, supports energy and mineral decisions, strengthens water infrastructure, and promotes economic growth.
- 7.8k employees
8
Yale School of Medicine· New Haven, Connecticut, United States
Founded in 1810, the Yale School of Medicine is a world-renowned center for biomedical research, education and advanced health care.Among its divisions are one of the nation’s oldest schools of public health and the internationally recognized Child Study Center, founded in 1911. Its Yale Cancer Center is one of 41 comprehensive cancer centers designated by the National Cancer Institute, and the school was one of the first 12 institutions to launch the Clinical and Translational Science Awards program in 2006. Its 33 academic departments include 10 in the basic sciences, 18 in clinical fields, and 5 in public health.Affiliated institutions include the 1,541-bed Yale-New Haven Hospital—flagship of the Yale New Haven Health System and one of the largest hospitals in the United States since acquisition of the Saint Raphael campus—and the Connecticut Mental Health Center, Pierce Laboratory, and VA Connecticut Healthcare System in nearby West Haven.The School of Medicine consistently ranks among the handful of leading recipients of research funding from the National Institutes of Health and other organizations supporting the biomedical sciences, and belongs to medical organizations including the Association of American Medical Colleges (AAMC) and the Association of Academic Health Centers (AAHC).The school’s unique curriculum, known as the Yale system of medical education, promotes teaching in small seminar, conference and tutorial settings, and requires student self-evaluation, independent thinking and investigation.Since 1839, Yale has required that each student complete a thesis based on original research prior to graduation. Graduates of the school have gone on to significant leadership positions in virtually every medical field, as well as many non-medical areas.
- 7k employees
9
RTI International· Durham, North Carolina, United States
RTI International is an independent scientific research institute dedicated to improving the human condition. Our vision is to address the world's most critical problems with technical and science-based solutions in pursuit of a better future. Clients rely on us to answer questions that demand an objective and multidisciplinary approach—one that integrates expertise across social, statistical, data, and laboratory sciences, engineering, and other technical disciplines to solve the world’s most challenging problems.For job openings and career information, visit www.rti.org/careers. RTI reserves the right to remove any inappropriate or unauthorized content posted or contributed to its LinkedIn page.
- Grant
- 6.6k employees
- Founded 1958
10
Oak Ridge National Laboratory· Oak Ridge, Tennessee, United States
Oak Ridge National Laboratory is managed by UT-Battelle for the Department of Energy. Scientists and engineers at ORNL conduct basic and applied research and development to create scientific knowledge and technological solutions that strengthen the nation's leadership in key areas of science; increase the availability of affordable, reliable energy; and contribute to national security.ORNL also performs other work for the Department of Energy, including isotope production, information management, and technical program management, and provides research and technical assistance to other organizations.
- Grant
- 6.5k employees
- Founded 1943

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Find engineers at AI companies in the United States

the United States has long been a hub for AI, and the list above ranks the largest AI companies headquartered there by current headcount, drawn from public LinkedIn and Crunchbase records. With 5,546 matching companies in Refolk’s index, this is a good map of where the AI talent in the United States lives - useful whether you’re recruiting, partnering, or sizing a market.

The biggest AI companies in the United States tend to be the gravitational centres for specialised talent - senior engineers, ML researchers, applied scientists, designers - while the smaller ones compete on speed, equity, and proximity to founders.

Refolk converts this list into a live search. Ask for “AI engineers in the United States hiring senior staff” or “founders of AI companies in the United States who left in the last 12 months” and Refolk returns a ranked shortlist with the evidence that earned each person a spot.

How this list is built

Refolk pulled AI companies headquartered in the United States from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 10 employees. The list refreshes monthly.

Last refreshed: Fri, 18 Sep 2026 07:44:03 GMT

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The list draws on the public company graph - headcount and growth signals, funding history, and recency. The criteria chips at the top show exactly which filters produced it, and the methodology section explains the ranking.

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