Y Combinator

Fusion may still sound like science fiction— but it might not be for much longer. With AI pushing demand for clean power to new highs, a breakthrough may finally be close.For Decoded, YC General Partner Gustaf Alstromer traces the history of fusion, the physics behind it, and the engineering challenges that stalled it for nearly a century. He also looks at how Helion is approaching the problem differently, as they develop a new fusion system expected to deliver power to Microsoft by 2028.

In this episode of The Breakdown, Tom and Dave are joined by fellow YC General Partner Pete Koomen to lay out a new vision for how AI should actually work: not as a chatbot bolted onto legacy software, but as a customizable tool that helps people offload the work they don't want to do. From editable system prompts to agents that act more like collaborators, they dig into what it means to build AI-native software—and why the future belongs to products that let users teach machines how to think.

Coding agents are no longer a distant idea—they're already starting to reshape how we work.YC's Tom Blomfield and David Lieb discuss how AI coding tools are transforming software development, why small, high-agency teams will be able to do what once took armies of engineers, and why there's never been a better time to start something new. They explore the bigger picture too: a future where there's abundance, knowledge work becomes more accessible, and founders have more leverage than ever before.If you're thinking about building, there's no better moment than right now.

AI can't yet one-shot an entire product—but with the rise of vibe coding, it's getting close. YC's Tom Blomfield has spent the last month building side projects with tools like Claude Code, Windsurf, and Aqua, seeing just how far you can push modern LLMs. From writing full-stack apps to debugging with a single paste of an error message, AI is becoming a legit collaborator in the dev process. This is a playbook for anyone who wants to get the most out of vibe coding and build faster.

Imagine ordering groceries and having them show up at your doorstep in just 10 minutes. That’s the promise of Zepto, the fastest-growing e-commerce company in India. In this episode of How To Build The Future, Garry sits down with Aadit Palicha, the co-founder and CEO of Zepto, to discuss how they got started in a Whatsapp group, what it’s like going up against incumbents like Amazon and Zomato and how the future of e-commerce is changing in the age of intelligence.

Not long ago, America led the world in building and innovation. But over the past 50 years, bureaucracy and red tape have made it nearly impossible to get big things done.Still, there’s a growing movement to turn that around — to build faster, smarter, and better than ever before.In this episode of The Main Function, Garry sits down with Atlantic staff writer and Plain English podcast host Derek Thompson to discuss his new book Abundance (co-authored with Ezra Klein). They discuss how we got here, what needs fixing, and what a bold, more prosperous 2050 could look like.

In this special episode of Design Review, Aaron sits down with Raphael Schaad, the Head of Calendar at Notion to discuss his leap from designer to founder, why illustration is an important first step when building a new product, and what ultimately makes designers uniquely qualified to start a company today.

12 years after starting DoorDash, co-founder & CEO Tony Xu and his employees still do deliveries every year, staying true to their core value: customer obsession.Today, DoorDash is the largest food delivery platform in the US.In this episode of How to Build the Future, Tony explains how their unwavering long-term vision won — helping create a new market while surviving near death and a global pandemic along the way.

Gusto (https://gusto.com) made payroll and HR painless for small businesses, growing into a $9.6B company along the way. Co-founder & CEO Josh Reeves joined YC's Harj Taggar to share how they built a payroll company from scratch and their customer-first approach to product design and culture.

Design isn’t just about making things work—it’s about how they work, says Dylan Field, the co-founder & CEO of Figma.As AI transforms tech, he believes a designer's judgment, taste, and agency will matter more than ever.Dylan sat down with YC's Garry Tan to discuss the evolving world of design in the age of AI, the challenging early days at Figma, and how his team forever changed the way designers and engineers collaborate.

YC General Partner David Lieb sits down with Aravind Srinivas, the co-founder and CEO of Perplexity, to discuss his origins in Silicon Valley, what it's like to compete with Google, and what the future of search could look like.Apply to Y Combinator: https://ycombinator.com/apply

Imagine flying from NY to London in just a few hours. That’s the future that Blake Scholl and his team at Boom Supersonic are working towards. Blake started as a software engineer and pivoted mid-career to aviation. Now, he’s at the forefront of trying to bring back supersonic travel for all of us. In this episode of Hard Tech, YC’s Jared Friedman visited Blake in the Mojave desert to find out how someone who didn’t have a background in aerospace engineering was able to build the first-ever independently developed supersonic plane.

Many startups fail because they run out of money. So how should you think about how to spend the money you raise?In this episode of Office Hours, YC General Partners Brad Flora, Pete Koomen, Nicolas Dessaigne, and Gustaf Alströmer discuss how to spend responsibly at each stage of a startup— including advice on when to hire, whether to invest in marketing and what spending mistakes to avoid.Apply to Y Combinator: https://ycombinator.com/apply

According to OpenAI's former Chief Research Officer Bob McGrew, reasoning and test-time compute will unlock more reliable and capable AI agents— and a path to scale to AGI. In this episode of How to Build the Future, YC's @garrytan sits down with Bob to discuss the lessons learned from his time at OpenAI, scaling laws, his advice for startups, and what all of this means for the jobs of the future.

AI continues to improve at an exponential pace. So what can you do as a founder to take advantage of it? In this episode of Office Hours, YC Partners discuss what you should consider if you’re thinking about pivoting to or incorporating AI as part of your startup.

In this episode of How to Build the Future, Garry sits down with Parker Conrad, Co-founder & CEO of Rippling, the all-in-one HR, Finance, and IT software company that’s valued at $13.5 billion. Parker is the co-founder of two unicorns and has one of the more dramatic startup journeys in recent years. In this interview, he shares his origin story, the lessons learned from his first two companies, how AI is changing the game, and why he thinks the future will be defined by "compound" software startups.

Two-time founder Rujul Zaparde knows a thing or two about resilience and learning from failure. After dropping out of college to build FlightCar, he worked as a PM at Airbnb, and later as a visiting partner at YC. In 2020, he co-founded Zip, a procurement software company that has since raised $370 million and reached a $2.2 billion valuation. In this conversation with YC's Dalton Caldwell, Rujul demystifies the world of enterprise sales, shares his hard-earned lessons about scaling a business from zero, and explains how founders can use first-principles thinking to better approach the challenges of building a startup.

YC General Partner David Lieb’s story is all about perseverance. In 2008 he co-founded Bump, one of the hottest startups of the early iPhone era. But even with 150 million users, he couldn’t find a way to create a sustainable business. For many founders, that would be the end of the road. But he didn’t quit there. Instead, David and his team pivoted several times, got acquired, and eventually went on to build Google Photos. In this episode of Backstory, he shares his advice for finding the right idea, what mistakes to avoid, and how to maintain a positive mindset no matter what gets thrown at you.

YC's Nicolas Dessaigne was the co-founder and CEO of @algolia, a Search API used by millions of developers to build great search experiences into their apps and websites. Today it powers over 1.75 trillion searches annually for 17,000+ customers worldwide. In this episode of Startup School, @dessaigne shares his advice for founders building a dev tools company from the ground up— covering everything from team and idea to GTM and sales.

Since Twitter rebranded to X, the platform has added new features and implemented a few major updates to both its UX and algo. So what can founders interested in product design learn from all this? In the first episode of our new series, The Breakdown, YC’s Tom Blomfield (co-founder of Monzo) and David Lieb (creator of Google Photos) take a closer look at X to find what lessons there are for founders building consumer products.