General Partner @YCombinator. Previously co-founder @CreativeMarket.
San Francisco
Joined April 2009
- Tweets5.8K
- Following673
- Followers111K
- Likes6.4K
Aaron Epstein retweeted
Today, I’m excited to announce Lapis is partnering with Walmart to enable the next generation of businesses to scale customer acquisition.
Working with Fortune brands is not new to us but the scale of Walmart is unlike anything we’ve ever seen before. Two in three Americans visit Walmart every month, and worldwide, over a hundred million people walk into a Walmart every week.
As agents take over user interaction with the internet, physical stores like Walmart become even more important being one of the few places which humans still visit regularly.
We’re proud to work with the Walmart team to make accessing hundreds of millions of SKUs super easy in an agent-native interface, and starting today, Lapis customers can advertise on Walmart with zero additional setup.
If you are a brand that wants more eyeballs on the largest physical storefront in America, we'd love for you to check it out.
Aaron Epstein retweeted
Our robot is live in our lab! In only a month we’ve opened our own lab in Mountain View, have deployed our first robot, and are working with our first client.
Building all of this in the middle of YC has been a massive challenge, but every step brings us closer to our vision of flexible robotic scientists capable of independently performing experiments across scientific disciplines. Couldn’t be more proud of our team.
P.S. This video is a screen recording of us remotely controlling our robot in the lab!
Alessandro has an incredible story. He was originally going to be part of the P26 batch to help bring cancer drugs to market faster, when he was diagnosed with cancer himself.
He's since beat it, and is doing his life's work building NxtCure, an AI CRO using digital twins of humans to test cancer drugs before they reach patients.
Congrats on the launch @alessandrohammd!
NxtCure Labs (backed by @ycombinator) just launched! We are an AI CRO with digital twins that test cancer drugs before they reach patients. We are 28% better than even the best frontier AI models. Oncology Trials take 10+ yrs, ~3% approved, 90%+ fail post-animal. Let's get new oncology drugs through trials!
Find anything about anyone @ploid_ai
Introducing Ploid Deep Research
You can now see everything
> Ask about anyone and get their full digital footprint in minutes
> Photos, videos, every social account, even the ones you'd never find (like WeChat)
> Works inside Claude, Codex, or any agent
Try it today at ploid.com
Aaron Epstein retweeted
honored to see @discoveredmat on the announcement 🫡 🚀
Aaron Epstein retweeted
Really excited about this model. The gap between us and previously SOTA STT models like ElevenLabs, Nvidia, AssemblyAI, Google, Meta is surprisingly large. Proud of our tiny team taking on the titans. Try it out on the AirCaps API, first 5h free.
Introducing A5S Async V1: the world's most accurate speech recognition model for speaker-attributed transcription.
#1 on VoiceArena, ahead of ElevenLabs, AssemblyAI, Deepgram, NVIDIA, Meta & more.
The next-best model makes 41% more errors across 5 public benchmarks.
And yes, every lab says they're #1. So we open-sourced our benchmark.
Try it now👇
Aaron Epstein retweeted
Introducing A5S Async V1: the world's most accurate speech recognition model for speaker-attributed transcription.
#1 on VoiceArena, ahead of ElevenLabs, AssemblyAI, Deepgram, NVIDIA, Meta & more.
The next-best model makes 41% more errors across 5 public benchmarks.
And yes, every lab says they're #1. So we open-sourced our benchmark.
Try it now👇
Aaron Epstein retweeted
20 years ago there was a building in SF that was nicknamed the Y Scraper because so many YC founders lived there. They just had a reunion and it makes me so happy to see them all. One thing you can say for sure about YC: no investor's founders become closer friends.
Aaron Epstein retweeted
We are building, and we will take you along!
Aviern (YC F26) is building unmanned cargo airplanes, and we want to show you how we do it.
Aaron Epstein retweeted
Introducing Aspen: an open-source Git server built for agents.
One 8-core server sustains 567 pushes a second to a single repository, each push stored before git prints "ok". Stock git, nothing to install on the client.
This is the personal agent Apple should’ve built. On-device, supports ApplePay, and even local passwords.
Cloud VMs keep getting hacked, so we built the first on-device iPhone agent
Introducing Result
> Cards & passwords stay on-device
> Run openweight models on your compute or cloud
> Native Apple Pay & Passwords
> Works in the background even when locked
result.dev/ios
Aaron Epstein retweeted
Carolynn and I are back for a special episode with Blake Scholl of @boomsupersonic about their amazing recent transformation, from losing Rolls Royce as their engine supplier to financing development of the airliner by selling gas turbines.
pod.link/1677066062/episode/…
Aaron Epstein retweeted
Not saying I have PFM but it’s not uncommon for us to sign annual contracts and angel checks in the same email.
Today I'm announcing Workers IO to solve the slowest part of engineering, verification!
AI agents can now write years’ worth of code in days, but it still takes significant engineering effort to verify what’s being built.
It’s impossible to predict all scenarios that could lead to a failure and that’s why most expensive failures are found in production.
Workers IO runs millions of simulated production scenarios on your entire system, including dependencies. These simulations run inside a deterministic hypervisor which injects faults like network delays, disk errors, clock skew, and process failures to verify how your system handles these conditions.
Deterministic execution allows us to systematically explore the state space of the system and perfectly reproduce failures.
We are already helping customers do years worth of production hardening in days and build confidence in what they’re shipping.
If you are working on systems that you can never afford to break, DM me and we can help you battle test them!
Aaron Epstein retweeted
Today, we announce five Grand Challenges in Material Science. We’re also committing $1M in prize money to anyone who can solve these challenges.
AI can solve Millennium Prize problems in math. Can it do the same in material science?
To find out, we reached out to 10 leading professors to identify the hardest open problems in the field.
Aaron Epstein retweeted
Last October, I started @simantic because I saw firsthand how embedded and firmware engineers were struggling to take advantage of the recent developments in frontier AI models.
In software, AI models are able to generate the code, run testing in simulation, and deploy to production, end-to-end without human input other than the first prompt. In firmware and embedded software, AI can generate great code, but any validation work is left to the engineer to run manually, on physical devboards or HIL setups.
We're building the simulation layer to solve that. We're giving AI the visibility into hardware that it needs to fully close the gap in fully autonomous hardware development, without the physical bottleneck.
If you're part of a firmware or embedded team looking for a better and faster way to test your code in simulation, email us at founders@simantic.dev
Simantic is the simulation layer that lets engineers and AI agents test and validate firmware at the speed of software.
Frontier AI models have made generating firmware code cheap and effortless, but testing still depends on manual hardware debugging, expensive equipment, and software designed more than a decade ago. Simantic is modernizing firmware testing with simulation built for the era of coding agents.
w/ @ycombinator @shong0504 @enough_ahnaf
Conductor is joining Meta!
It's been so cool to see their evolution from pivot hell during the S24 batch, to building a product that they themselves wanted to use (back in the stone age of 2025 when people still coded by hand!), to building a community and movement around their product.
All of their success is so well deserved, couldn't happen to better people.
Congrats @charlieholtz @jacksondecampos and the entire @conductor_build team!
I am very excited to share that Conductor is joining Meta!
We have some big, crazy plans for the next interface. If you liked Conductor, you’re gonna love what’s coming.
We’re super excited to work with @natfriedman and @alexandr_wang at MSL to build it. They’ve been on an absolute tear, and I’m convinced MSL has the highest talent density of all the labs.
A huge thank you to our earliest believers @aaron_epstein, @ilyasu, and @nabeel. And to everyone here who tried Conductor, sent us feedback, and prompt requests - you made this so much fun. Thank you ❤️🚂
Choo choo!
The simplest way to build an audience is to just share what you're working on, but most founders don't do it because creating and editing video content is too painful.
Vyra just makes it so easy now, it's like having a dedicated video editor on your team. Def check it out!
Introducing Vyra!
We're building the personal video editing agent for shortform content. Just upload your raw footage, prompt, and Vyra edits it for you.
Try now at usevyra.com
Primordiant is building general-purpose robot scientists to programmatically run physical experiments at a massive scale.
Imagine data-center-sized laboratories full of robot scientists, where anyone can call up a physical experiment as easily as a cloud GPU, and run it at a scale no human lab could match.
An intelligent machine needs three things: a brain, senses, and hands.
We gave AI a brain. We taught it to see. Now we're giving it hands.
Models can propose a thousand hypotheses, but breakthroughs come from testing them.
Today we're launching @primordiant : general-purpose robot scientists that run experiments at scale.
AI mastered bits. Now it's time for ATOMS.
