Founders Fund AI portfolio in San Francisco

Contrarian venture firm investing in deeptech, defence, and breakthrough software. Filtered to AI companies headquartered in San Francisco.

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Ranked by current headcount across Founders Fund-backed AI companies in San Francisco. Refreshed daily.

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
Until· San Francisco, California, United States
We are building reversible cryopreservation technology to solve the organ procurement and matching problem.Cryopreservation is already essential to modern medicine — powering IVF and life-saving stem cell therapies. Now, we’re extending this technology to whole human organs — transforming hours of viability into weeks, or months, however long is necessary — so that no donated organ is lost to logistics, and no patient dies waiting. By solving this immediate need, we de-risk and build the foundation for what comes next: whole-body reversible cryopreservation. We're pausing molecular motion to give patients a bridge to future cures.
- Series A
- 56 employees
- Founded 2021
3
NewLimit· South San Francisco, California, United States
NewLimit is a biotechnology company working to radically extend human healthspan. We’re developing medicines to treat age-related diseases by reprogramming the epigenome, a new therapeutic mechanism to restore regenerative potential in aged and diseased cells. We leverage functional genomics, pooled perturbation screening, and machine learning models to unravel the biology of epigenetic aging and disease using experiments of unprecedented scale.All correspondence from NewLimit will come from an @NewLimit.com email address.
- Series C
- 55 employees
- Founded 2022
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4
UNITY Biotechnology· South San Francisco, California, United States
UNITY is harnessing pathways of aging biology to develop new medicines, with a focus on retinal diseases. As pioneers in cellular senescence, UNITY is advancing the first senolytic therapeutic candidate for retinal diseases that aims to restore diseased tissue to a healthier state, a potentially paradigm shifting treatment in ophthalmology.
- Post-IPO debt
- 19 employees
- Founded 2009
5
Siren Biotechnology· San Francisco, California, United States
The fight against cancer needs new, big, bold ideas. At Siren, we’ve got one: Universal AAV Immuno-Gene Therapy.We are combining two transformative therapeutic technologies – AAV gene therapy and cytokine immunotherapy - into a single, reimagined modality that overcomes key challenges and redefines how we destroy tumor cells and elicit anti-tumor immunity.
- Grant
- 10 employees
- Founded 2020

6
Stemcentrx, Inc.· South San Francisco, California, United States
Founded in 2008, Stemcentrx combines state-of-the-art research and GMP manufacturing capabilities. This has allowed us to advance from target discovery in our laboratory to treating patients in clinical trials at an accelerated pace. We are investigating many of the largest and most lethal cancers through our proprietary platforms that identify cancer stem cells, discover novel targets, engineer and manufacture antibodies and antibody drug conjugates.Our mission is to develop therapies that cure and significantly improve survival for cancer patients. We are pioneering new approaches to eliminate cancer stem cells, which initiate and perpetuate tumors. Stemcentrx has assembled a talented and motivated team committed to this mission. We are recruiting people with world-class expertise in their practice, versatility, high energy and an entrepreneurial spirit. Our state-of-the-art laboratories and manufacturing facilities are located in South San Francisco, California. We have a driven, ambitious, focused, hard-working, apolitical, fun, and collaborative culture that is more typical of Silicon Valley startups than large pharmaceutical companies. Our employees are compensated with salary, benefits and stock options.
- Series G
- 6 employees
- Founded 2008

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Founders Fund-backed AI companies in San Francisco

The list above ranks Founders Fund-backed AI companies headquartered in San Francisco by current headcount, drawn from public LinkedIn and Crunchbase records. With 6 matching companies in Refolk’s index, you can see exactly where Founders Fund’s AI thesis has landed in San Francisco.

Three filters - investor, industry, city - narrow the field to a tight cluster of operators with overlapping incentives. They share a thesis, a network, and a market. Hiring from this list usually means hiring someone already inside the Founders Fund AI world in San Francisco.

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How this list is built

Refolk pulled AI companies headquartered in San Francisco whose disclosed Crunchbase investor list includes Founders Fund, ranked them by current employee count, and kept those with at least 3 employees. The list refreshes once a day.

Last refreshed: Wed, 05 Aug 2026 17:37:47 GMT

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