Geoff Ralston
About Geoff Ralston
Geoff Ralston is the founder of the Safe Artificial Intelligence Fund (SAIF) and is based in San Francisco, California. According to Crunchbase, he studied computer science and electrical engineering at Dartmouth College (1982) and Stanford University (MS, 1987), and he holds an MBA from INSEAD (1992).
His operating career began in engineering. At Four11 he built RocketMail, an early web mail service that became Yahoo Mail in 1997. At Yahoo he ran the communications business unit and later became Chief Product Officer. He was then CEO of Lala, a music startup that Apple acquired in 2009. In 2011 he co-founded Imagine K12, an education technology accelerator whose companies included ClassDojo and Remind. Imagine K12 merged with Y Combinator in 2016.
Ralston joined Y Combinator as a partner around 2011 to 2012. Crunchbase dates his time as president and partner from May 2019 to December 2022. He left YC at the end of 2022 and launched SAIF in April 2025. Crunchbase counts two companies he has founded.
Crunchbase records 36 investments across 34 portfolio companies for Ralston, with 15 exits, two of them by IPO. It lists no lead investments. Other data providers report different totals, and those totals depend on how each provider counts deals, so treat the figures as approximate.
The public deal records show a long run of seed and pre-seed checks. Tracxn lists a seed round in Nervana Systems in April 2014, a seed round in Triplebyte in September 2015, and a Series A in Hatch in October 2015. NFX Signal lists a seed round in Rain Industries in September 2023, a pre-seed round in Locunity in July 2025, and a pre-seed round in Asymmetric Security in January 2026. A third-party aggregator also lists many early education companies, which fits his work at Imagine K12. His personal angel check size is not reliably public.
His main AI vehicle is SAIF. TechCrunch reported on April 17, 2025 that Ralston was returning to formal investing with a fund aimed at startups that enhance AI safety, security and responsible deployment. SAIF's stated themes include AI alignment and interpretability, security infrastructure to protect AI intellectual property, governance and compliance tools, and systems to counter AI-generated misinformation. One summary of the fund says it avoids investing in fully autonomous weapons.
Per Wikipedia, Ralston said in a June 2026 interview that biosecurity was the main focus of his AI safety work at that point. He also writes about AI safety on his Substack and posts about safety organizations on X.
Earlier AI-related exposure includes Nervana Systems (seed, 2014). AngelMatch also lists Hugging Face among his past investments, but it gives no date.
SAIF targets early-stage companies. Its announced check is $100,000 as a SAFE with a $10 million cap. Maginative reports that portfolio companies also get weekly office hours with Ralston, coaching on Y Combinator applications and introductions to his investor network. The fund is based in the United States and focuses mainly on U.S. companies.
Before SAIF, his investing spanned edtech, developer tools, marketplaces, enterprise software and consumer products, mostly in the United States. In a 20VC interview, Ralston discussed the investor's role in giving founders perspective and warned against "profile investing". The public record does not give a total fund size or a number of planned investments, and he has not published a check size for his personal angel deals.
- Asymmetric Security: pre-seed round in January 2026, per NFX Signal and PitchBook.
- DeepResponse: PitchBook records the investment in 2025. It is categorized as network management software.
- Locunity: pre-seed round in July 2025, per NFX Signal.
- Meter: PitchBook records an investment in February 2024.
- Rain Industries: seed round in September 2023, per NFX Signal.
- Accredible: digital credentialing company. Ralston is an advisor, and Grokipedia reports he joined its Series B in May 2023.
- Triplebyte: seed round in September 2015, per Tracxn.
- Hatch: Series A in October 2015, per Tracxn.
- Nervana Systems: seed round in April 2014, per Tracxn.
- Mailgun: email API company, listed by Tracxn and EasyVC as a past investment.
- crunchbase.com/person/geoff-ralston
- en.wikipedia.org/wiki/Geoff_Ralston
- finance.yahoo.com/news/former-y-combinator-president-geoff-193328109.h
- maginative.com/article/former-yc-president-geoff-ralston-launches-fund
- superscout.co/investor/saif-safe-ai-fund
- signal.nfx.com/investors/geoff-ralston
- pitchbook.com/profiles/investor/106015-96
- tracxn.com/d/people/geoff-ralston/__RAGNcekL7LOceljnubFQcUJw0zXnSF9LpA
Investing activity
Geoff Ralston has made 36 investments according to Crunchbase across 34 portfolio companies, and has seen 15 exits, 2 of them by IPO and founded 2 companies.
Deals
Frequently asked questions about Geoff Ralston
Who is Geoff Ralston?
Geoff Ralston is the founder of Safe AI Fund and a former president of Y Combinator. He created RocketMail, which became Yahoo Mail, was CEO of Lala, and co-founded Imagine K12.
How much does Geoff Ralston's Safe AI Fund invest?
SAIF announced $100,000 initial checks as a SAFE with a $10 million cap. Ralston has not published a total fund size.
What kind of AI startups does Geoff Ralston invest in?
SAIF backs early-stage startups that improve AI safety, security and responsible deployment. Themes include alignment and interpretability, AI security infrastructure, governance and compliance tools, and countering misinformation.
Does Geoff Ralston lead rounds?
Crunchbase lists no lead investments for him, out of 36 recorded investments. Founders should not assume he will set the terms of a round.
What support does Geoff Ralston offer founders beyond capital?
Maginative reports that SAIF companies get weekly office hours with Ralston, help with Y Combinator applications and introductions to his investor network.
Where can founders contact or follow Geoff Ralston?
He is on X as @gralston and on LinkedIn, and he writes on Substack at geoffralston.substack.com. SAIF's website lists the fund's application process.
Is Geoff Ralston an angel investor?
Yes. Geoff Ralston invests personally as an angel and is Founder at Safe AI Fund. Crunchbase counts 36 investments and 15 exits.
Where is Geoff Ralston based?
Geoff Ralston is based in San Francisco, California, United States.
How can founders reach Geoff Ralston?
Founders on Lounge can see Geoff Ralston's contact details in AI Investor Contacts (paid plans), check for a warm introduction through members who worked with them under Warm Paths, and add Geoff Ralston to their Investor Pipeline to track the conversation.