YC Visiting Partner, former CEO/Cofounder of Convex (acq by $TTAN), physical and vertical AI, services, & industrials investor. Dad.
San Francisco, CA
Joined February 2026
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- Following92
- Followers949
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Charlie Warren retweeted
Discovered Materials, a months-old YC startup that uses AI to find chip materials, is offering $200,000 for each solution to five open materials science problems.
spr.ly/6011BH0LE7
Apply.
The deadline to apply to the YC W27 batch is tonight at 8 pm PT!
If you’re making something people want, we’d love to hear from you.
ycombinator.com/apply
Just getting started
Your first enterprise customer is the hardest one to get.
At YC, they come to you.
Last week we launched Early Access Network: 30 companies, 100+ enterprise leaders, one room, months before Demo Day.
Now part of every YC batch. Apply for W27 by Nov 2: ycombinator.com/apply
Charlie Warren retweeted
Atoms are the new bits. 25% of YC startups now build hardware, so we're setting up a YC Hardware Lab in Dogpatch.
We're hiring the person to run it. If you've built hardware and know your way around a shop, apply or send us someone great: ycombinator.com/careers?job_…
MechE + fine art + Apple = @enrico_milletti.
Pumped to see him launch @silicamachines today
Robot arms that train physical AI can't feel anything lighter than a tennis ball. Silica's actuators can feel a paperclip.
Introducing Silica.
We make actuators 50x more sensitive at an affordable price, so that robots can feel the world around them.
When I was at Apple, I developed technology that helped humans live more creative and connected lives.
Now I make hardware for the training age, so that robots can begin to share that world with us.
We just opened pre-orders. Check out silicamachines.com to learn more.
I've seen the rise of voice agents up close in vertical AI companies. And then the latency issues + skyrocketing costs of using exclusively closed models.
@hopper_research solves both of those.
Excited for the launch today --
There’s a huge blindspot in the inference market today: it’s built almost entirely for coding agents.
Voice is how billions of people will interface with AGI. That’s what we’re building at @hopper_research : the inference cloud for voice
Excited to launch today at withhopper.com
SaaS is evolving by natural selection. EveryApp is what's next.
Most horizontal software should be rebuilt for agents and open source.
@bensenescu already did it with OpenSEO: 25K+ GitHub stars, with all organic, crazy fast growth. CRM + Analytics are now live.
Launching today 👇
Charlie Warren retweeted
You've been grinding on S-1 teardowns for years. Dozens of boring SaaS companies. The time is now. This is your moment.
The AI infrastructure build-out is short on workers. I've seen it firsthand with former customers building data centers.
@shepherd_si is taking it on. Wiring takes dexterity at the frontier of robotics, and few teams can pull it off.
Thrilled to back them at @ycombinator.
Introducing Shepherd Robotics (YC F26).
We’re building robots for data centers and advanced manufacturing—starting with equipment testing, inspection, and electrical wiring & assembly.
Bring capacity online faster. Increase production.
youtube.com/watch?v=UAw41QkF…
I got to see @FarzaTV up close in P26. Refreshing to see a real builder do his thing. More behind the scenes of how he ships and launches 👇
There’s a misconception that a successful launch video needs to cost tens of thousands of dollars and feel like a high production commercial. But @FarzaTV has a different approach.
Farza is the founder of @heyclicky and previously built Buildspace, one of the largest online schools for people working on their own ideas. He’s been making videos for over a decade, and today his posts regularly get millions of views. Rather than treating launches as rare, high-stakes moments, he’s made them part of the everyday process of building a company.
Farza sat down with YC’s @aaron_epstein to share his playbook for turning demos into stories people actually want to watch. He breaks down how he scripts videos that still feel off the cuff, why founders should launch constantly, and and how to figure out which channels actually convert.
01:44 — Launch Constantly
03:38 — Start Shipping Demos
05:02 — Show the Process
06:07 — The Clicky Launch
07:43 — Write a Hook That Stops the Scroll
10:30 — Why Farza Scripts Every Video
12:04 — Designing the First 10 Seconds
15:15 — Demo-Driven Development
17:25 — You Have to Take a Thousand Shots
20:48 — Farza’s Formula for Videos That Convert
23:01 — Turning Demos Into Stories
24:53 — Show What You're Actually Building
29:11 — Finding Customers on Social Media
31:02 — Which Platforms Actually Convert?
39:01 — Why Farza’s First Hire Was a Filmmaker
40:49 — The Video Stack
45:41 — The 30-Day Launch Challenge
Charlie Warren retweeted
Attended @ycombinator early access event yesterday evening!
AI is making software faster to build. A new generation of startups is building the tools to run, test, and improve it.
Five companies worth a closer look:
Boxes — Cloud computers for coding agents, letting teams run Claude Code and Codex in parallel.
Founders: Nick Bushak (@nbushak) and Drew Regitsky (@drewregitsky), both previously at Gem.
Caveman — Helps AI agents use fewer tokens and run more efficiently, reducing the cost of getting work done.
Founder: Julius Brussee (@julius_brussee).
Rystic — Builds simulated APIs so developers can test software and agents without depending on live services.
Founders: Zachary Kiihne and Evan Whitehouse.
Simulithic — Sends AI users through your app across devices and browsers to find broken flows, without manually writing every test.
Founders: Ryan Ning (@itsnotryan) and Satyam Singh (@KlausCodes).
ObsessionDB — A real-time data warehouse built for agents to ingest and query large amounts of data efficiently.
Founders: Rafael Aviles (@avilesrafa), Marc Höffl (@marchoeffl), and Marc Leuthardt (@marcmacmac).
Also great to reconnect with my friend from Harvard, Charlie Warren (@charliewarren), now a Visiting Partner at YC and previously cofounder and CEO of Convex.
My takeaway: faster development creates demand for better testing, infrastructure, and reliability. There’s room for significant companies across that stack.
Which other early-stage companies should I be following?
Company links in the reply below.
The internet may be melting. But I'm still getting unsolicited texts to sign up for new payroll software before the end of the year. We're gonna be alright.
Charlie Warren retweeted
The top end of growth rates for companies riding an AI tailwind just keeps accelerating.
@sequoia is leading our Series C at a $1B valuation.
We started Blacksmith in 2024 to make CI faster and less painful. In January we ran 5 million CI jobs a week. Today it's over 90 million and growing, and we’re still early.
ALT Line chart of weekly CI jobs run on Blacksmith, growing from 5.4M in January to 90.5M in October 2026.