Top AI companies in San Francisco

Companies building AI products, foundation models, and applied ML platforms. Filtered to companies headquartered in San Francisco.

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Ranked by current headcount across AI companies headquartered in San Francisco. Refreshed monthly.

1
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
- 10.5k employees
- Founded 2015
2
Gladstone Institutes· San Francisco, California, United States
Gladstone's mission is to drive a new era of discovery in disease-oriented science and to mentor tomorrow’s leaders in an inspiring and diverse environment.Although Gladstone shares traits with other top life science organizations, we pride ourselves on taking uncommon scientific paths to overcoming disease. Our investigators are selected to become authorities in leading or creating new fields, and we work to provide them with resources to explore bold new thoughts, form effective scientific teams, and create or master emerging research technologies that accelerate progress—Gladstone’s special recipe for success that has yielded some of the most important biomedical advances of our time.Our three disease-focused institutes constitute the core of our discovery engine, but do not operate in isolation. We are seizing unprecedented opportunities for “convergence”—defined as the blending of intellectual and physical assets from multiple scientific disciplines and fields to speed the discovery process in our attack on unsolved health problems that affect almost every human family.
- Grant
- 599 employees
- Founded 1979
3A
AI Researcher· San Francisco, California, United States
AI Researcher - Creating the future through safe Artificial Super Intelligence
- 418 employees
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4
Alfa Overseas, Mumbai· San Francisco, California, United States
Knowledge process outsourcing Company located at Mumbai, India Areas supportedData entryResearch Bookeepingweb DesignInternet marketing SEO Alfa makes life better for companies of all shapes and sizes - from one man bands to large multinationals - We help you Unlock profits - by streamlining your business processes, ease the management of your business & reduce your operating costs!
- 218 employees
- Founded 2003
5
Redrob· San Francisco, California, United States
Redrob - 'border' in reverse - is building LLMs for the next 3 billion. Purpose-built for sales, recruitment, and jobs. Series A funded with $14M. Backed by world-class VCs.
- Series A
- 218 employees
- Founded 2018

6
Midjourney· San Francisco, California, United States
Midjourney is an independent research lab exploring new mediums of thought and expanding the imaginative powers of the human species.
- 208 employees
- Founded 2022
7
NCIRE - The Northern California Institute for Research and Education, Inc.· San Francisco, California, United States
NCIRE - The Northern California Institute for Research and Education, Inc. - has one mission and one goal: Veterans' Health. We are the leading nonprofit research institute in the United States devoted to advancing Veterans' health research.NCIRE is part of one of the world’s most dedicated and successful Veterans care communities, pioneering new treatments and understandings of military medicine and care. We take seriously our obligation to understand and meet the health challenges facing all generations of military Veterans. Through new technologies, novel scientific insights, and international clinical collaborations, we strive to set a new standard of health care for Veterans and military personnel.If you are interested in a career with NCIRE - the Northern California Institute for Research and Education, please visit our website www.ncire.org.
- Grant
- 164 employees
- Founded 1988
8
Public Policy Institute of California· San Francisco, California, United States
Public Policy Institute of California (PPIC) is a nonprofit, nonpartisan think tank. We are dedicated to informing and improving public policy in California through independent, objective, nonpartisan research.Since 1994, PPIC has helped California’s leaders to better understand policy issues by providing them with research that is free of partisanship or ideological biases. Today, we are a highly respected resource on a range of critical issues—encouraging productive dialogue and inspiring the search for sustainable solutions in Sacramento and across the state.Learn more at http://www.ppic.org
- 111 employees
- Founded 1994
9
Arena· San Francisco, California, United States
Created by researchers from UC Berkeley, Arena (formerly LMArena) is a community-powered platform to measure and advance the frontier of AI for real-world use. Tens of millions of builders, researchers, and creative professionals come to Arena to use frontier models and give feedback on their responses, shaping a public leaderboard grounded in real-world use.
- Series A
- 96 employees
- Founded 2025
10
Vitalant Research Institute· San Francisco, California, United States
Vitalant Research Institute is dedicated to advancing global transfusion and biologics safety, availability, and effectiveness through innovative research and education.Established more than 50 years ago, the Research Institute has become a world-renowned institute engaged in research ranging from blood donor epidemiology to cellular therapy to virus discovery.The Research Institute has state-of-the-art equipment to support research related to blood and blood product safety in the areas of molecular biology, immunology, virology, tissue culture, cell processing and epidemiology. It also supports the education and training of the next generation of researchers through fellowships, internships, mentoring and classes conducted in San Francisco and around the world. Please follow Vitalant on LinkedIn for updates related to Vitalant Research Institute.
- 95 employees
- Founded 1959

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Find engineers at AI companies in San Francisco

San Francisco 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 117 matching companies in Refolk’s index, this is a good map of where the AI talent in San Francisco lives - useful whether you’re recruiting, partnering, or sizing a market.

The biggest AI companies in San Francisco 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.

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How this list is built

Refolk pulled AI companies headquartered in San Francisco 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: Mon, 14 Sep 2026 10:09:30 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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