What got us from 0 to 1 isn't what will get us from 1 to N.
3 years ago, before the launch of ChatGPT, we set out to start a company that most people thought was impossible.
To be honest, many people still think it's impossible today.
Multiple rounds of rejection and external doubt later, we went from 0 to 1 and created the category of "Digital Minds". We built an exceptional team and earned the backing of investors like Sequoia and Founders Fund.
It wasn’t easy. There were probably moments we should have pivoted.
But we kept pushing.
Today we work with some of the top minds in their fields - @lennysan, @bhalligan, Eckhart Tolle, Vanessa Van Edwards, Dr. Mark Hyman.
Delphi is the place people go to learn from them, get their advice, and access their expertise.
Looking ahead, we believe Delphi is how every human will represent themselves in the AI age. A new way for people to meet, connect with, and learn from one another.
But to get there, we need to evolve.
Delphi is looking for a VP of Engineering - someone who has taken a consumer platform from 1 to N and knows the tradeoffs required to build infrastructure that supports millions. An AI-native builder and culture carrier.
In the early years, I had an almost allergic reaction to "experience" - I believed purely in slope over y-intercept. As we've scaled, I've come to understand that to get where we want to go, we need someone who has already been there.
If that's you, or someone you know, I want to talk.
One of Xfund’s greatest honors is to have backed the archetypal liberal arts founder @DanielNadler twice -- in his first company @Kensho upon his graduation from @Harvard; and now, at @EvidenceOpen. https://t.co/O5oDCkgIDy
THE LIBRARY OF MINDS: EPISODE 1 - starring Keith Rabois (@rabois)
An OG member of the PayPal Mafia, co-founder at OpenDoor, Managing Director at Khosla Ventures, and one of Delphi's earliest believers.
We discuss:
• Lessons learned building PayPal, LinkedIn, Square, $OPEN & more
• Early career inflections: from litigation to Silicon Valley operator
• Why joining great teams is underrated, especially vs. starting your own company
• The new physics of AI startups (and org design mistakes to avoid)
• Why stretching & Slack are actually bad for you
Plus: What makes a winning office culture, advice for scaling from 20 to 100, building moats in AI, and why vacations might be overrated.
(00:00) — Intro
(00:56) — Who is Keith
(03:13) — Can you judge a startup by its office?
(04:28) — Litigator to PayPal Mafia, zero business experience
(08:52) — Start a company, or work for someone great?
(11:15) — All-nighters and culture at PayPal
(13:03) — Do vacations mean you hate your life?
(16:05) — Square’s zero-defect rule
(17:23) — Speed of adaptability vs. speed of execution
(21:35) — Is AI sustaining or disruptive?
(25:53) — Why stress is good for you
(28:14) — Building moats in AI
(30:39) — The downside of Slack
We are so thrilled to have been @StevenGlinert and team’s first partners in Sphere Semi -- today the company announces its Series A to make AI-designed chips the default. If you’re in business operations, AI, and chip design: get in touch. We’re hiring!
Our amazing portfolio company @withdelphi is about to blow your mind with its Library of Minds. This isn’t just another podcast - it’s the first interactive podcast where you can talk to the guest’s digital mind after the episode.
@TheCeoX@VCBrags I'm not really on X. I've tweeted a grand total of 4 times in 2025--all basically anodyne, corporate press-release-type things (sometimes written by others). My attention may sometimes drift during work meetings, but I do *not* tweet during them. Very sorry you thought this!
We are deeply honored to have been @chalk’s first investor — the team led by @marcff, @marx_elliot, and @Derander are powering the most important part of the AI revolution now underway: inference. We long ago inferred that they’re the team to back. 💪🏼
“These ends will not be achieved by assertions of power, unmoored from the law, to control teaching and learning at Harvard and to dictate how we operate.”
“No government—regardless of which party is in power—should dictate what private universities can teach, whom they can admit and hire, and which areas of study and inquiry they can pursue.” - President Alan Garber https://t.co/6cQQpcJVTd
“We don't think three years ahead because AI is so fast-moving... the first three months this year have moved faster than the last two years... nobody saw DeepSeek coming.” (and then, @AravSrinivas named Shiv his favorite Roy sibling--the one he’d choose to take over Perplexity).
With @HBSRock and @innovationlab, we were thrilled to bring @perplexity_ai CEO @AravSrinivas to Harvard in an electrifying series of events. Aravind was the guest judge at Xfund’s pitch competition and met with fellow scholars at Harvard and MIT. Students found him captivating!
What do people think *you* sound like? Try @boldvoiceapp’s amazing new accent guesser: and see if you can fool it by putting on your best foreign accent! https://t.co/kc3uSJLCQw
.@HarvardHBS just posted this video of me and Sam Altman at the @Xfund Assembly 2024. I was Sam’s very first investor, and presented him with the first pitch deck he ever gave me at age 19 in an event co-hosted by @HarvardHBS and @hseas: https://t.co/K8EaUi7r6r
He was the very first founder I ever invested in, and I was his very first investor. I presented @sama with the first pitch deck he ever gave at age 19 and we had fun tracing our origin story, and the future, in a packed event co-hosted by @harvardhbs, @harvardseas, and @xfund.
What if the world’s foremost experts could scale their reach infinitely, making their knowledge and experiences accessible to everyone?
As of today, they can.
Excited to unveil our digital cloning platform @with_delphi for public use.
We are honored to partner with @Chalk. Our partnership also marks a meaningful personal milestone: the privilege of backing a distinguished alum of @whiffenpoofs. Thank you to @marcff, @Derander, and @marx_elliot for entrusting us to be your accompaniment on this journey!
I'm thrilled to share -- it's a big day for @chalk ! It's been incredible to be on this journey with @Derander, @marx_elliot and our team.
A huge thank you to @htaneja, @jvrionis, and @patrickchung for betting on us and helping us get to this milestone
https://t.co/Y1CzPq7mjO
If you're in SF on December 3, please join (for free!) a really fun crowd: it's Toys for Tots 2023 at the The Westin St. Francis in Union Square. RSVP here: https://t.co/6izvNqAPmu
1/ Meet @with_delphi, a digital cloning platform that captures your thinking, making your knowledge, experiences, personality, and opinions available to others in a personalized way.
Delphi allows you to have personalized one-on-one conversations with your audience at scale.
In a remarkable achievement, @xfund portfolio company @EvidenceOpen “has become the first AI in history to score above 90% on the USMLE.” Congratulations to repeat Xfund founder @DanielNadler and his brilliant team. https://t.co/azf4mDjkQW