Y Combinator

Inside Theranos with ex-Employee Tyler Shultz

23K views · 2d ago · 2:56:16

Guest: Jessica Livingston

With Theranos and Elizabeth Holmes back in the conversation, we’re revisiting one of the most remarkable firsthand accounts of what actually happened inside the company. Tyler Shultz joined Theranos fresh out of Stanford as a true believer in its mission. His grandfather, former Secretary of State George Shultz, sat on the company’s board, and Elizabeth Holmes had become a mentor and even a presence at family gatherings.

Topics: Tyler Shultz’s Theranos Story · Meeting Elizabeth Holmes · The First Red Flags · Theranos Launch Day · Inside the Theranos Lab · How Theranos Built a Culture of Fear

Is AI Now Good Enough To Cure Cancer? | YC Paper Club

51K views · 5d ago · 1:21:43

This week’s Paper Club is all about AI for biology. The cost of sequencing has collapsed, which means biology now generates more data than anyone can mine, and the models are finally catching up.

Topics: Is the Turing test solved? A live experiment · Why now is the best time for AI Bio · Alfredo Gonzalez: cancer as a data problem · Yusuf Roohani: virtual cells and autonomous research · Garyk Brixi: what a model learns from DNA · Divya Nori: few-shot prompting for biological design

How To Build The Future: Paul Graham & Amjad Masad

85K views · 6d ago · 44:15

Replit was building toward the AI coding era years before it had a name. In 2024, the company shipped an agent that could take a request in plain English, work through errors, provision its own infrastructure, and keep going until the software actually worked. The model companies even reached out to ask how Replit had pulled it off.

Topics: "You guys basically invented vibe coding" · Watching users copy-paste from ChatGPT · The origins of Replit · People underestimate their ability to predict the future · Grieving the craft · A culture of obsessing over users

How Boom’s Biggest Crisis Became Its Biggest Opportunity

16K views · 7d ago · 47:15

Guest: Blake Scholl

In this Social Radars episode we talk with Blake Scholl about one of the cleverest business model transformations in the history of startups: Boom's move into building gas turbines. When Rolls Royce pulled out as Boom's engine supplier, it seemed to many like fatally bad news. But instead it not only helped Boom solve boomless supersonic flight, but also enabled them to tap a huge new revenue stream to fund development of the airliner.

Topics: Rolls-Royce Walks Away · The Breakup Goes Public · Deciding to Build the Engine In-House · The Brian Chesky Advice That Changed Everything · Why Building the Engine Was the Right Call · Unlocking Boomless Supersonic Flight

10 Habits PhDs Must Unlearn To Build a Startup | Startup School

57K views · 9d ago · 9:51

Guest: Startup School

Google, Anthropic, and Databricks were all started by founders with PhDs. But they’re the exceptions. Most academic founders fail, because the instincts that get you published are the ones that can get you killed in a startup. Francois Chaubard knows both sides. He’s a visiting partner at YC and a current PhD student, and before that he was a researcher in Fei-Fei Li’s lab and the founder and CEO of Focal.

Topics: Why academics struggle as founders · Vanity metrics vs. what people want · Interesting vs. important · Novelty vs. plagiarism · There is no finish line · Get on a plane and talk to people

Engineers Make Great Founders

33K views · 10d ago · 2:39

A lot of what makes a great engineer also makes a great founder. Before starting Layers and BootLoop, Shivani Patel and Chris Markus worked at SpaceX, where they learned to take ideas from zero to one, solve hard problems, and own the outcome.

The $1B Company Fixing AI’s Software Bottleneck

39K views · 11d ago · 9:13

Blacksmith (YC W24) is building a faster cloud for continuous integration (CI), helping developers test and ship code as AI coding tools generate more of it. As software production accelerates, testing and validation are becoming the new bottleneck. That shift has helped Blacksmith grow 20x over the last year, and the company recently raised a $66 million Series C at a $1 billion valuation.

Topics: Making CI Faster With Gaming CPUs · Winning Over Investors and Developers · Scaling CI for the AI Coding Era

What Happens When Everyone Can Build Software

116K views · 14d ago · 48:46

Guest: Paul Copplestone

In this episode of the Lightcone, the hosts sit down with Paul Copplestone, co-founder and CEO of Supabase. Since starting in the YC summer batch of 2020, the company has exploded to 13 million users and over 50 million databases under management. Supabase is now positioning for a future where everyone can write their own software, billions have access to personal databases and agents are driving much of the demand.

Topics: Growth and 4x Revenue · Three Eras of Supabase · “Builders” vs. Traditional Devs · Personalized Apps · Personal Databases & Data Ownership · Scaling to Billions

Own Your Intelligence

68K views · 16d ago · 1:29

Most companies building with AI still rent their intelligence from frontier labs. As open models improve, more companies will want models they can run, train, and control themselves. The opportunity is to turn a company’s workflows, expertise, and failures into specialized models that improve with the business.

The New Full-Stack Designer

149K views · 18d ago · 1:05:44

Apply to Y Combinator Work at a startup Here is the link for the Grass Shader Github Repo if you want to try it out

Topics: How the design process has changed · Inside Shopify's product design studio · Molly, the Brooklyn studio · The Collins bookshelf · Toby's mandate: the future needs to be designed · How the studio works inside Shopify

Why Inference Matters 12x More Than Training | YC Paper Club

70K views · 20d ago · 1:50:49

This week’s Paper Club is all about inference. For every FLOP spent training a model, roughly six go to serving it each year — and getting that part right has produced over $220 billion in market cap in the last decade. But inference is much more than calling model.forward. Every token has to move through a complicated stack of routing, caching, scheduling, kernels, memory, and hardware, all while balancing speed, cost, and quality.

Topics: Why inference matters more than training · Three kinds of inference innovation · Dan Fu: the lifecycle of an inference request · Jeff Morgan: not all open model tokens are the same · Joe Fioti: compiling models with search, not heuristics · Liangsheng Yin: SGLang and memory for the agent era

This Is How You Should Actually Make Launch Videos

68K views · 21d ago · 47:09

Guest: YC’s Aaron Epstein

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 Farza Majeed has a radically different approach. Farza is the founder of Hey Clicky and previously Buildspace, one of the largest online schools for people building their own ideas. He’s been making videos for over a decade and his posts regularly get millions of views.

Topics: A different approach to launching · Demos, not launches · The Hey Clicky launch video · Why views don't matter · The "did my eyes stop" test · Scripting videos that sound unscripted

How To Stand Out In A World Of AI Designs

50K views · 22d ago · 47:43

Magic Patterns (W23) is one of the fastest-growing design tools in AI, helping product teams turn ideas into interactive, code-backed prototypes in minutes. Alex Danilowicz and his co-founder, both front-end engineers, built Magic Patterns to solve a problem they had themselves: finding a better way to turn ideas into something visual. They were among the first teams building prompt-to-design tools back in 2023.

Topics: What is Magic Patterns? · From YC Pivot to Product-Market Fit · Staying Ahead as AI Design Tools Improve · Demo: Designing With Magic Patterns · MagicOS · Designing With Context on a Canvas

AI Safety Fact vs. Fiction | YC Paper Club

41K views · 27d ago · 1:37:07

This week’s Paper Club is all about AI safety - not the headlines, the science. AI safety has been a research field for decades, with its own conferences, methods, and a track record in systems like aircraft collision avoidance, where the standard is one catastrophic failure per billion flight hours.

Topics: Science fiction vs. science fact · Engineering problem, or P(doom) · What actually happened at Hugging Face · Where "10% in 10 years" comes from · The real risk: open weights in the wrong hands · Clark Barrett: when AI met automated reasoning

Demis Hassabis: Put your life force into a problem that matters

17K views · 28d ago · 2:33

Guest: Demis Hassabis

Alexandr Wang on what matters in an age of abundant intelligence

103K views · 1mo ago · 1:25

What surprised PG about AI

25K views · 1mo ago · 1:52

How Jeetu Patel Runs Cisco Like the World’s Largest Startup

33K views · 1mo ago · 43:23

Cisco is building AI infrastructure, from networking GPU clusters to securing agents, with its hyperscaler AI business reaching $9.3 billion in orders in two years. Cisco President and Chief Product Officer Jeetu Patel joins Y Combinator Managing Partner Jared Friedman to discuss bringing startup speed to 32,000 engineers, why AI should unlock new ideas rather than just cut costs, and why he expects to need more engineers, not fewer.

Topics: Cisco’s Bet on AI · Running Cisco Like a Startup · The Infrastructure AI Agents Need · Getting 32,000 Engineers to Embrace AI · Bringing AI to Hardware and Silicon · Inside the AI Data Center Buildout

A camera that can see through walls

29K views · 1mo ago · 2:01

Applied Electrodynamics is building cameras that can see through walls and other opaque materials. Using radio waves, their system can see through drywall, marble, and other surfaces to locate studs, pipes, cables, junction boxes, and other objects hidden behind them, then turn that data into a dimensionally accurate 3D model.

What If We Stopped Using GPUs? | YC Paper Club

76K views · 1mo ago · 1:20:35

This week’s Paper Club is all about alternative compute. Modern AI has been shaped by a tight coupling between transformers, backpropagation, and GPUs. But as compute efficiency starts to plateau, there may be very different ways to build the machines that come next.

Topics: Francois Chaubard: Why Alternative Compute? · Beyond Backpropagation · Zero-Order Optimization and SOMA · Ilker Oguz: Computing With Light · Why Optical Computing Isn’t Everywhere Yet · Building a Diffusion Model With Light

Robotic factories that build robots

15K views · 1mo ago · 1:51

Tensr is building robotic factories that build robots. Their 12,000-square-foot factory is already making humanoids, end effectors, and even robots for the International Space Station. Every order becomes training data for the factory to manufacture the next one better.

Robot-Use Agents: Why General-Purpose Models May Win in Robotics

82K views · 1mo ago · 29:49

Guest: Robot-Use Agents

One of the biggest surprises in AI over the last few years has been how well coding agents generalize beyond software. In a recent essay, MIT professor Philip Isola argued that we may be entering the era of robot-use agents: general-purpose models that can control different robots, write policies, and learn new physical tasks with little or no robot-specific training.

Topics: The Bitter Lesson for Robotics · From Coding Agents to Robot Policies · In-Context Learning vs Model Training · Building a Harness for Robot Control · Turning Robot Actions Into Reusable Skills · How AI Models Learn the Physical World

Rocket cargo delivery anywhere on Earth in minutes

14K views · 1mo ago · 2:23

Hop Aero is building rockets that can deliver cargo anywhere on Earth in minutes. They’re starting with military logistics and other time-sensitive payloads, including temperature-controlled materials with short shelf lives, where getting something there much faster can materially change the outcome.

Autonomous construction on Earth and beyond

19K views · 1mo ago · 2:24

A lot of construction work is still done by hand simply because the machines to automate it don’t exist. That’s become a bottleneck for building things like solar farms, data centers, and other critical infrastructure. Cosmic Robotics is building those machines. Their robots have already installed 11,000 solar panels, and they just signed a major contract with the largest construction company in the country.

Drone swarm defense

18K views · 1mo ago · 1:43

Attack drones are reshaping modern warfare, but many countries still lack an effective way to defend their airspace. Earendil Robotics is building autonomous interceptors, along with the software and training needed to stand up that capability from scratch. Their systems can take off, transit, and intercept targets on their own, reducing months of pilot training to a few clicks.

The State of Startups in 2026

219K views · 1mo ago · 36:29

YC works with thousands of founders every year, which gives us an early look at how startups are changing. Right now, the shift is striking: startups are moving from bits to atoms, nearly one in five YC companies has a solo founder, and companies are reaching meaningful revenue faster than ever.

Topics: Startups Are Moving From Bits to Atoms · Why AI Is Making Hard Tech Easier · Defense, Manufacturing, and the Return of Hard Tech · AI Compute Is Becoming a Physical Infrastructure Problem · Robotics Is Approaching Its ChatGPT Moment · Software Isn’t Dead. It’s Becoming the Harness

Why You're Getting Zero Replies To Your Cold Emails

101K views · 2mo ago · 12:42

The best outbound starts before you automate anything. Founders need to learn who actually has the problem, what gets their attention, and what makes them reply. YC Visiting Partner Christina Gilbert recommends doing at least your first 100 outreaches by hand so you can learn those things yourself.

Topics: Targeting beats perfect messaging · How to find the right job titles · Picking the right companies · Intent signals · Craft a message worth reading · Subject lines

Mass Magnetics: USA-made magnetics for robotics and defense

20K views · 2mo ago · 2:51

Guest: Mass Magnetics

Magnets are becoming critical to the future of robotics, defense, and other major US industries. But 90% of rare earth magnet material is conventionally thrown away. The team at Mass Magnetics are recycling magnets from old EV motors into new ones, with the goal of making American magnets at scale.

Introducing Early Access: An Invite only program for the Enterprise

10K views · 2mo ago · 1:13

Guest: Introducing Early Access

Introducing the YC Early Access Network. 4x a year, senior technology leaders get early looks at YC's enterprise AI companies and help shape their roadmaps. Invite-only, by application. Fall '26 kicks off Oct 22 in SF. Apply now

Why The Harness Matters More Than The Model | YC Paper Club

433K views · 2mo ago · 1:00:11

Harnesses get dismissed as just scaffolding, just prompt engineering, and not real research. But that couldn't be farther from the truth. The same model weights that score 30% on ARC-AGI score 95% with a better harness. So we gathered a group of researchers and founders working at the frontier to do a deep dive into the state of harnesses.

Topics: Why harnesses matter · Building an auto-researcher by accident · A five minute history of harnesses · Self-improving harnesses · Tonight's speakers · Seth Karten: Prime Agent, a self-improving RLM harness

Paul Graham on what motivates founders

28K views · 2mo ago · 1:49

Paul Graham on what drives founders through the hard parts “Being dutiful is not enough. The obstacles are too fearsome for mere dutifulness.” “You know what actually motivates founders day to day? The fear of failure.” “If your server’s crashing, you’re not thinking, ‘I got to deal with this because if I deal with it, I’ll become a billionaire.’ You’re thinking, ‘Oh no, the server’s crashing. It will be a disaster.

Hard Tech Startups Are Built One Milestone at a Time

10K views · 2mo ago · 1:26

At Heart Aerospace, Anders Forslund built the company one material milestone at a time, using each one to earn the credibility and capital to build the next. “We really had no technology. I came to YC Demo Day with a little 3D-printed model.”

Open Models Change The Economics of AI

124K views · 2mo ago · 57:16

Ollama (YC W21) is used by 9 million developers and 85% of the Fortune 500, giving co-founder and CEO Jeffrey Morgan a unique view into which AI models people are actually using and how that’s changing. Right now, the biggest shift he sees is toward open models, driven by coding agents, falling costs, and capabilities that are rapidly catching up to the frontier labs. On Ollama Cloud, that shift has driven a 150x increase in token usage since the start of the year.

Topics: Who's Actually Using Open Models? · Is It All About Cost? · The Token Usage Explosion · Fine Tuning: Hype Cycle or Here to Stay? · Where Open Models Beat Claude · Launching Models at Scale

Paul Graham On Startups, Ambition, and Great Founders

374K views · 2mo ago · 21:25

Guest: Paul Graham

YC Visiting Partner Vivian Shen sits down with Paul Graham at the original YC office in Mountain View to talk about startups, AI, ambition, and what makes great founders. Apply to Y Combinator Work at a startup

Topics: 21 Years of YC · Why Today’s Startups Are More Ambitious · Frighteningly Ambitious Ideas · What Actually Motivates Founders · What Makes a Founder Formidable · What Surprised PG About AI

The World’s Largest Electric Aircraft Just Flew

4.2M views · 2mo ago · 14:49

Heart Aerospace (YC W19) just flew the largest electric airplane ever flown — a 100-foot wingspan, a takeoff weight of 25,000 pounds, and $5 of electricity to get it off the ground.

Max Junestrand: You Need The Willingness To Learn Faster Than Anyone Else

97K views · 2mo ago · 59:40

Guest: Max Junestrand

Today, more than 3% of the world’s lawyers use Legora, and the company has grown from $1 million to $100 million in ARR since launching in October 2024. Transcript Apply to Y Combinator Work at a startup

Topics: What Lawyers Actually Needed · The Origin Story · Moving Into a Law Firm · The YC Rejection · San Francisco · 80 Investor Meetings in 10 Days

Going In Deep On Data | YC Paper Club

46K views · 2mo ago · 52:35

This week's YC Paper Club is focused on data. Three domain experts give talks to break down the challenges and frontiers of training data, benchmarks, and multilingual pre-training. Apply to Y Combinator Work at a startup

Topics: Francois Chaubard: Why a whole night about data? · Vincent Sunn Chen: The Art & Science of Benchmarking Agents · Volo Kuleshov: Inception: Diffusion Language Models for Production · Shayne Longpre: ATLAS: Practical Scaling Laws for Multilingual Models

Michael Kratsios: Inside the White House's AI Strategy

11K views · 2mo ago · 39:44

Guest: Michael Kratsios

Michael Kratsios has seen the AI boom from both sides: as COO of Scale AI and inside the White House. Today, as the director of the White House Office of Science and Technology Policy, he helps shape America’s national strategy on AI, science, and emerging technology.

Topics: Michael Kratsios on AI Policy and Public Service · From Tech to the White House · How Technology Policy Actually Gets Made · The White House on Open Source AI · How Washington Sees AI Differently · Regulating a Technology That Changes Every Six Months

Susan Kare: Designing Icons & Graphics For the Original Mac

47K views · 3mo ago · 51:45

Guest: Susan Kare

Susan Kare joined Apple as an art history PhD who barely knew anything about computers. She went on to design many of the icons, typefaces, and symbols that helped make the original Macintosh feel understandable and human, defining a visual language for personal computing that still influences software today.

Topics: Making Things Meaningful and Memorable · How Susan Joined Apple · Designing the Original Macintosh · A Computer Anyone Could Use · Creating Chicago and the Mac Typefaces · MacPaint and the First Icons