Before Alex Lee joined Magic Patterns (W23), he was running his own company, Iago — one that's still self-running today. But when his former Robinhood colleague Teddy co-founded Magic Patterns, a tool that helps product designers create interactive mockups and prototypes, Alex saw something he couldn't pass up: an AI-first approach to a problem he'd hit himself while building new features at Iago. "It's pretty clear that Figma is going to be replaced and a company like Magic Patterns is here to replace it," he says.

Technically, Alex was employee number two — a sales hire came first — but he was already working part-time before he officially started.

Why Magic Patterns

Alex and Teddy stayed in touch after Robinhood, texting about startups and sharing philosophies about work and engineering. "I felt like I aligned really well with Teddy and Alex (Danilowicz)" — the co-founders — "and how they thought, and felt like I'd not only grow but grow with the company if I joined."

The problem space pulled him in, too. Magic Patterns is used by more than 3,000 product teams, and Alex gets a front-row seat to how those teams are reshaping design in an AI world. "Especially as the different product team roles — eng, design, product — start to blend, it's super interesting to see how fast everything's evolved, and stay on top of it."

Owning problems, not just features

"You're not just a code monkey, you're a product person," Alex says. "Things move so fast at a small company that you don't just own features, you own problems. And when you find solutions, you're in charge of finding the next set of problems to solve."

That means coding, yes — but also improving the onboarding funnel, talking to customers, and jumping on support. One weekend, Alex noticed users weren't just making designs but building slide decks to present those designs to leadership. So he built out an entirely new file type with full slide deck features over the weekend and shipped it. "A big company wouldn't even let me ship this without talking to the right team who 'owned' this product surface."

He also landed on the front page of Hacker News with a side project done at work: an agent that builds Rollercoaster Tycoon-influenced theme parks from a prompt.

The daily toolkit

Alex dogfoods Magic Patterns itself to design new features. Once something is ready to implement, his workflow looks like this:

• Cursor and Claude Code, always on the latest models
• Cursor connected to Slack — he prompts it directly for small bug fixes and features
• An internal code reviewer agent called Patterson that reviews code before it ships
• Three clones of the same GitHub repo instead of worktrees, so he can work on features in parallel

Transparency as a feature

Alex says the thing that surprised him most about startup life is how transparent it is. "Everyone at Magic Patterns knows the financials, growth rate because the founders trust us, but also because they are building a very open and transparent culture." He actually thinks large companies carry more hidden risk. "You never know when they might lay people off or have a change in direction."

The founders, Teddy and Alex D., foster a culture of trust and autonomy. "They're incredibly receptive to feedback and will always take action on it."

Now that the team has grown to ten people, Alex has taken on more interviewing and has become the dedicated forward-deployed engineer for enterprise customers, especially around Magic Patterns' Design Systems vertical — the top-requested enterprise feature.

Who should join

"If you're early in your career, make a polarized bet," Alex says. "You'll work more than a typical 9-5 but you'll be learning a lot more in return." If you want real ownership, the chance to ship a feature over a weekend, and a view overlooking Coit Tower from a new San Francisco office, Magic Patterns is hiring an engineer who wants to build the world's best AI design agents.

Vin Bui was on a leave of absence from Cornell when he found Nowadays. He had just left his own YC company from the Winter 2025 batch and was back on campus, not enrolled, scrolling through Work at a Startup looking for what came next. A dog logo caught his eye. "It felt childlike in a way, and that unique taste is what originally attracted me," he says. Then he looked at the website. "This website needed a lot more work. I really like seeing companies that have things I know I could fix."

He sent a message to co-founder Anna, went through the interview process, and became the first full-time hire at Nowadays (S23), a San Francisco company that uses AI to make planning corporate events simple. When it started, Nowadays was selling to small startups. Today it’s the platform Fortune 500 companies like Google, Airbnb, and BlackRock use to bring their people together.

Acting as the technical founder

Vin joined the company as employee number one, and the first technical hire. "As engineering hire #1, you’re basically a technical founder," he says. "Everything I do is exactly what I would've done if I were the technical founder of my own company."

That meant building engineering from the bottom up, setting up processes, leading SOC 2 compliance, handling security, and becoming the main point of contact for anything touching engineering or IT. He talked with heads of engineering at other companies to figure out what good looked like, then built it himself. "No mentorship exists, right? You have to mentor yourself."

Why he said yes

Vin evaluated Nowadays the way a founder would evaluate a co-founder. He looked at two things:

• Could he have impact? During the work trial, he immediately saw what the codebase needed. He had the background to fix it and knew he could build something meaningful.
• Could the founders make the company succeed? Having been a YC founder himself, he watched how Amy and Anna worked — how they presented the company, attracted customers, and communicated their plans. "These two know exactly how to present the company. Working with them, I understood how competent they are and that I could rely on them."

He also asked them directly about their plan for the future. "The way they answer and the way they sound tells you whether they've actually thought it through. I really like people who think."

Building AI voice — and everything else

When asked about the coolest thing he has built at Nowadays, Vin lights up about AI voice: building systems that call hotels and negotiate with them on behalf of clients. "Voice is very similar to how humans work, so it's very interesting to see how close AI can get to us."

His daily setup reflects someone who cares about craft. He uses Ghostty for his terminal, Claude Code CLI over any GUI, and orchestrates different AI models depending on the task. "I'm not the type to use the biggest model for everything. Using the right model for the right thing matters a lot." He writes his own custom skills and workflows, tests every new model that comes out, and browses Twitter to find tools worth trying. "I love building my own workflow."

At a big company, he says, you might spot something great for the product but can't act on it. At Nowadays, it's different. "I observed something and have a great idea, let me just build it."

From builder to the person the team bounces ideas off of

Nowadays is now an 11-person team, and Vin's role has evolved. He still builds, but he has become the first person teammates come to when they have a big idea they haven't fully thought through. "I wouldn't call myself a manager, because I don't manage anyone. I trust them and give them full autonomy." He triages tricky problems, then hands them off to the right person to go deeper.

He is also quick to point out something that surprised him about startup life: you can have a life outside of work. "Amy has a kid, and Anna loves exercising and has been running marathons. We're a health-first type of team, and we care about each other." He values that the founders work hard and still make time for families and friends.

Who would thrive here

Vin is direct about what early startup life demands. "You need to be able to trust yourself, because the main person who can help you is yourself. You need to be self-reliant and constantly learning on your own." But it should also feel good. "You spend so much time with them that it should feel like being back in college, working on something with your friends."

If you want the intensity of a founding role without investor talks, if you want to pick your own problems and ship fast, and if you want to work with people you would genuinely spend time with outside of work — Nowadays is hiring.

Ryder Kemper was in Ohio, winding down a startup he and his college friends had built together. The team had decided to close it — not because it failed, but because they wanted different things. Ryder knew he wanted to stay in startups, and he knew he wanted to be in San Francisco. A message on Work at a Startup from Corgi Insurance's first sales hire changed everything. He did a thirty-minute interview on a Friday, flew to SF on Sunday for a work trial, and never went back. "By the time I had an offer, I had already helped to get the signature Costco mattresses into the house we were living in."

Corgi Insurance (YC S24) is rebuilding core financial infrastructure from the ground up — insurance systems, policy administration, claims — with the goal of owning the stack end to end.

The Mystery Machine test

Ryder's work trial was not a whiteboard exercise. He spent roughly half his time writing code and the other half riding in the company's Mystery Machine bus, hauling furniture to a new office. That ratio told him something important about the kind of place Corgi was. "The energy was just different. I felt like there was a good chance of success but worst case scenario it would be a great time."

He calls himself employee number seven. His self-assigned title: Chief Furniture Mover.

What he actually builds

Ryder has touched nearly every part of Corgi's technical stack:

• Core policy administration and claims systems
• New product development as Corgi launches additional insurance lines
• Hiring processes for new engineers and teams

The claims system is the project he talks about most. Working closely with adjusters who "think its all magic and crazy how fast we can put stuff together," he gets fast, enthusiastic feedback that makes the next iteration easier to ship. The loop is tight: build, get it live — sometimes before it feels fully ready — then iterate on real feedback from customers and the sales team.

His current tool of choice is Claude Code. He recently set up a desktop at home he can shell into remotely, letting his AI agents run even when his laptop is offline. One trick he likes: having Claude generate artifacts beyond terminal output — diagrams in Figma, recorded videos of pull-request work — to make its output more understandable to the rest of the team.

Why the people matter

"The concentration of talent here is really crazy," Ryder says. What stands out to him is the default posture: no idea is too big, no challenge gets waved off. "The default answer is always 'yea we can do that,' or 'why don't we just do it ourselves.'" The founders give people real freedom to operate, and Ryder says he has learned a lot about business just by watching how they navigate situations nobody on the team has seen before.

He also notes, with equal sincerity, that he was surprised by how much milk co-founder Nico can drink.

Two years, ten years of work

Ryder estimates he has packed about ten years' worth of experience into roughly two. He has shifted between building, managing, and scoping new projects, but has stayed close to whatever Corgi is working on next. "To me everything still feels like a new startup." He has also discovered something unexpected about himself: he is happier with less stuff. Moving around frequently for work, he stopped accumulating things and found he didn't miss them.

He plans to start his own company one day. For now, Corgi is the place where he is learning how.

Who would thrive here

If you want clear boundaries and a narrow job description, this is not the role. If you want to ship fast, own entire projects end to end, and do whatever needs doing — engineering or otherwise — Ryder's advice is simple: "Expect a lot of uncertainty but also a crazy journey that has not really been matched by anything else in my experience. Expect to work extremely hard and constantly feel like there's never enough time for anything. Expect to learn a lot about yourself and make a new group of close friends."

Corgi Insurance is hiring. You can find them on Work at a Startup.

We’re thrilled to announce that Vivian Midha Shen and Raphael Schaad are joining Y Combinator as our newest General Partners.

Vivian and Raphael have spent the last two batches working closely with YC founders as Visiting Partners. We’ve seen firsthand what makes each of them exceptional: they combine deep technical experience with strong product judgment, and they know how to help ambitious founders turn an early idea into something users love.

Vivian co-founded Juni Learning (YC W18), an online academy for kids’ coding and math, and later founded Acely, an AI tutor for college readiness. Across the two companies, she built businesses with more than $50 million in revenue and millions of users. Acely alone grew from zero to $10 million in run rate with a lean team, showing what small, AI-native companies can accomplish.

Vivian has done nearly every job inside a startup: engineering, product, design, marketing, and whatever else needed to get done. Before becoming a founder, she worked as a software engineer at Google, a consultant at McKinsey, and Director of Product at Operator. She studied computer science and creative writing at Stanford. That range helps her judge both how well a product works and how much it matters to users.

Raphael founded Cron (YC W20), a next-generation calendar beloved for its craft, speed, and attention to detail. Notion acquired Cron in 2022, and Raphael went on to grow Notion Calendar to millions of users. He then served as Head of Design for Growth and new products.

Raphael moves fluently between design and engineering. Before Cron, he worked on the popular news reader Flipboard and the award-winning Markdown editor iA Writer. With his Swiss eye for design, he has spent his career making complex software simple. Raphael holds a BS in Computer Science from Bern University of Applied Sciences and an MS in Media Arts and Sciences from MIT. Founders building new products benefit from his instinct for what matters and his insistence on craft.

Vivian and Raphael have built companies from the ground up, and they’ve already shown how much they can help other founders do the same. As General Partners, they’ll work with companies from their first weeks in the batch through the years of building that follow.

We couldn’t be more excited to have them on the team. Welcome, Vivian and Raphael!

We're excited to announce that Christopher Golda and Grey Baker are joining Y Combinator as General Partners.

Chris and Grey have both been Visiting Partners at YC, where they've already made a big impact working closely with founders across multiple batches. Now, as General Partners, they'll play an even bigger role in selecting, advising, and supporting the companies we back.

Chris co-founded BackType (YC S08), a data infrastructure and analytics company acquired by Twitter in 2011. At Twitter, he launched and ran the Ad Center product, growing revenue to over $1B. Since leaving Twitter, he's been working directly with founders to help them find customers and raise capital, participating in early-stage rounds of companies like Benchling, Coinbase, Stoke, and Supabase. As a Visiting Partner, he's brought that combination of deep technical founder experience and a decade of pattern-matching across hundreds of early-stage companies to the founders he works with.

Grey co-founded Dependabot, a developer tool used by over a million people that was acquired by GitHub in 2019. Before that, he was an early employee at GoCardless (YC S11), joining when it was just six people and leading product and engineering as the company grew to over 100. After GoCardless, Grey cycled 29,000 km around the world, then came back and built Dependabot as a side project that took on a life of its own. He went on to co-found Pincites (YC S23), which was acquired by Filevine. As a Visiting Partner, he's brought a builder's mentality and firsthand experience scaling products from side project to millions of users to every batch he's been part of.

As General Partners, Chris and Grey will work directly with YC founders at every stage of their companies. We're super excited to have them on the team. Welcome, Chris and Grey!

We're thrilled to announce that Diana Hu has been promoted to Managing Partner at Y Combinator.

Diana first came through YC as a founder. She co-founded Escher Reality (S17), an augmented reality backend that was acquired by Niantic in 2018. Diana returned to YC in 2021 as a Visiting Group Partner, and joined full-time as a Group Partner in 2022. Over the past four years, she's become one of the most prolific partners in YC's history. She's worked with nearly 230 companies across 18 batches, logged over 2,100 office hours, and those companies are now worth a combined $7 billion.

Diana grew up in Chile and studied computer vision and machine learning at Carnegie Mellon. She built her technical foundation early: data science at OnCue before Verizon bought it, ML research at Intel Labs, then Escher Reality as CTO. At Niantic, she ran the AR Platform team and shipped AR to the 100M+ people playing Pokémon GO.

Few people have both built a startup from zero and shipped tech at that scale. Diana has done both. That combination, paired with deep technical experience in ML and AR, is exactly what today's founders need from a partner. Diana has been at the center of working with the builders pushing the frontier on AI, robotics, and hard tech, including breakouts like Avoca, Reducto, David AI, Salient, Stepful, and HappyRobot.

Congrats, Diana. We're lucky to have you.

We're thrilled to announce that Harshita Arora is joining Y Combinator as a General Partner.

Harshita has been a Visiting Partner at YC since the Summer 2025 batch, making her the youngest visiting partner in YC's history.

Harshita discovered coding at 13, dropped out of school at 15 to pursue it full-time, and by 16 had built Crypto Price Tracker, a crypto portfolio management app that was featured by Apple, which was subsequently acquired, and earned her India's Bal Shakti Puraskar, one of the country's highest honors for young achievers. She then received an O-1 visa, moved to San Francisco, and co-founded AtoB (YC S20).

Harshita and her co-founder came into YC with an idea that got killed by Covid, and with zero background in trucking or payments, they spent weeks visiting truck stops until they found the idea that would become AtoB. Today, AtoB is a Series-C stage company building financial infrastructure for the trucking industry. Often described as "Stripe for Trucking," it offers fleet cards, instant payouts, and modern financial tools, serving over 30,000 fleets across the US.

As a General Partner, Harshita will work directly with YC founders at every stage of their companies. She brings deep fintech and infrastructure experience, a founder's instinct for product, and the perspective of someone who's been building companies since she was a teenager.

We're super excited to have her on the team. Welcome, Harshita!

When we first met the founders of EquipmentShare in Winter 2015, they didn’t come from Silicon Valley or Wall Street. They came from rural Missouri: the “Show Me” state. Their background is one where you learned to build things yourself, fix what was broken, and work with what you had.

EquipmentShare’s founders grew up in a commune where rules were strict, and self-reliance wasn’t a slogan — it was a necessity. When they left, they didn’t have much. They certainly didn’t have Ivy League degrees. What they did have was something much better: a deep understanding of construction, contractors, and the everyday frustration of trying to get real work done with the wrong tools and the wrong systems.

The EquipmentShare founders didn’t start by trying to “disrupt” an industry. They started by solving their own problem. YC founder Paul Graham proselytized about solving your own problems in his essay about how to get startup ideas: “The most successful startups almost all begin … from things their founders built because there seemed a gap in the world.”

EquipmentShare started as a straightforward idea, which was to level the playing field for contractors by simplifying access to equipment, building a marketplace for construction machinery and unlocking more value from what they already owned. From day one, the company operated with a distinct rhythm: build first (before talking about it), ship fast (before optimization), and listen (obsessively) to customers.

YC’s motto is “Make something people want” and few companies embody that principle more literally than EquipmentShare.

Over time, they didn’t just build a marketplace. They built an operating system for the jobsite.  What started as a way to rent and share equipment grew into a national, vertically integrated platform that helps contractors manage fleets, track machines, and run their operations better. Their T3 telematics and software platform — built because customers needed visibility and control — became just as important to the manufacturing process as the iron itself.

Looking back at their original application, it’s striking how much of the DNA is still there: deep domain knowledge, relentless work ethic, and a refusal to accept that “this is just how the industry works.”

The EquipmentShare founders are certainly from the Show Me state: they showed everyone that great businesses don’t always start in obvious places, and that the most durable, legendary companies are built by people who truly understand the work on the ground.

Watching EquipmentShare grow from a scrappy Missouri startup into a company helping power jobsites across the country has been a privilege. This milestone is huge — and it also feels like just another step in their journey for a team that has been building steadily from day one.

EquipmentShare has always felt like a team of destiny, and we couldn’t be more proud to have been a part of your story. Congratulations to Jabbok, Willy, and the entire EquipmentShare team! We’re excited to keep watching you build.

This year, YC has partnered with nearly two dozen companies to offer students who attend YC events a suite of free credits for AI devtools.

The YC AI Stack includes over $20,000 in cloud credits on Azure and AWS, over $5,000 in credits for GPT/Claude/Grok, and generous credits for AI devtools in voice, browser automation, web search, video generation, databases, web crawling, and more. We’re especially happy that 14 YC companies are represented in this starter pack.

We would love to see students use these to experiment with the latest AI tools without worrying about paying for them out of pocket. Many of the best ideas are built on top of these technologies. For example, you could build a market research tool using Firecrawl and Exa, a voice assistant using Vapi and Browser Use, or a legal aide using Reducto and Gumloop.

At the moment, students who attend a YC university event starting in Fall 2025 are eligible to redeem a deal. You will receive an email shortly after your eligible event confirming your access to the program. We’re excited to work with our partners to continue rolling this out to more students in the upcoming year. Looking forward to seeing what you all build with this.

We’re excited to share the Demo Day dates for 2026 so founders, investors, and our broader community can plan ahead.

2026 Demo Days

Winter 2026: Tuesday, March 24

Spring 2026: Tuesday, June 16

Summer 2026: Thursday, September 10

Fall 2026: Wednesday, December 2

If you’d like to start researching companies ahead of time, check out Launch YC and the Startup Directory. New startups launch there throughout the batch, so it’s worth checking in regularly.

Investors can review past investments and keep their contact info and bio up to date in the YC Investor Portal. More information about attending Demo Day can be found at ycombinator.com/demoday.

We look forward to seeing you in person next year!

Today, Meesho, one of India's leading online retail and merchant tools companies, goes public. It is the second YC company to be listed in India.

We met Meesho’s founders, Vidit and Sanjeev, three months into their journey. They applied to the Summer 2016 YC batch just after they launched their website. According to their application, they had 300 users at the time. As with most beginnings of great startups, they had a pretty clear idea of the problem they were solving, but hadn’t figured out the solution yet.

Their problem was this: very small merchants represented a large percentage of the total online retail market in India, and those merchants were being underserved by the existing tool sets. Shopify and Bigcommerce, the existing tool providers at the time, were too expensive and too heavyweight for their needs. The example they gave during their interview was that of a homemaker who had a side business selling sarees to her friends and neighbors. She did this primarily over WhatsApp and Facebook.

While selling sarees to your neighbors didn’t scream ‘big opportunity’, the India-specific example was foreign enough to the two American and one Australian interviewers that it kept us on our toes. Going into the interview, we thought the Indian online retail market was already crowded, with the likes of Flipkart, Zomato, and Amazon India. But from their example, it became clear that we didn’t know what we didn’t know. The statistic that got our attention was that 3M Indians were selling (mostly apparel) on Facebook, and less than 5% had websites. For reference, there are a total of 3M small retailers (online and offline) in the entire US.  This was a big opportunity.

Meesho’s startup journey is not the tale of a rocketship to the moon. Rather, it was a decade-long grind of long days and disciplined product development. It is a tale of constantly asking customers what they need and then quickly and relentlessly iterating and testing solutions. It’s a tale of not shying away from hard problems. They started out by creating e-commerce tools that integrated with Facebook’s Graph API. These tools helped sell and track orders. The tools got better and better, and the number of merchants grew along with those improvements.

By staying close to their customer, the team soon realized that supply chain logistics and shipping problems were the biggest impediments to their merchants’ growth. But as we all learned during COVID, supply chains are complicated and fragile. Improving supply chains is a hard problem. Rather than shy away, they leaned in. By doing so, they not only solved their customers’ problems but also built a business that is not easily copycatted.

Next, they learned that their merchants wanted to drive more traffic in order to grow. Recognizing the growing importance of influencers and online content in purchasing decisions, they built tools for these creators in order to drive that traffic. Then, in 2021, six years after they started Meesho, they launched a consumer-facing app and website, competing with the likes of Flipkart and Amazon India. It turns out that India’s online retail market wasn’t that crowded after all.

Over the course of 10 years, Meesho has methodically built their company by relentlessly listening to their customers. They have followed where their customers’ problems led them. In doing so, they have helped India harness the energy of its small business entrepreneurs. Their tale should serve as a great example to all startups.

Vidit and Sanjeev are both humble people with unassuming demeanors. That exterior, however, belies relentless energy and a steely determination to change the world. We couldn’t be more proud to have been a part of their journey to becoming a public company and wish them the best on their journey forward.

Today, Groww, one of India's leading consumer fintech companies, goes public. Groww is India’s dominant digital investing platform, enabling tens of millions of people to invest simply and confidently in stocks, mutual funds, and ETFs. Groww is Y Combinator’s first company to list in India, and we could not be more proud.

When YC invested in Groww, we thought we understood what it meant to build a lasting company: to grow deliberately, focus on customers, and execute with discipline. But over the years, we’ve learned more from the Groww team about how to do that in India, or anywhere, than almost any team we’ve ever worked with.

YC’s motto is “make something people want,” and few companies have embodied this concept more completely than Groww. They grew organically, navigated through COVID, launched new products, and stayed relentlessly focused on their customers, always with quiet resilience and long-term conviction.

Looking back at our early notes on Groww, it’s remarkable how far they’ve come. We always believed this team could build, but what they’ve achieved has gone far beyond even our most optimistic expectations. They consistently exceeded projections, created products we never imagined, and scaled with a sense of purpose and clear focus. Over time, we realized we weren’t just supporting these great founders, we were learning from them. We talk a lot about guiding founders, but the best ones teach us just as much as we teach them. Groww has been that kind of company - the kind that reminds us why we do this work, and what a great management team actually looks like.

Outside of playing point guard for the New York Knicks, my job at YC is one of the best in the world. And one of the best parts of it is working with exceptional founders, the ones who build great companies and reshape entire industries. The Groww team is a standout in this elite group. Whether in San Francisco or at a strategy retreat in Mussoorie, spending time with them is a masterclass in thoughtful long-term company building. Watching Groww scale to become a public company in India is an incredible milestone, but it also feels like the natural next step for this team.

We (like other long-term investors) are selling a small portion of our Groww shares as part of the public offering to increase the float. But it’s the kind of sale anyone would make reluctantly - this is a stock you want to hold forever. If you believe in backing great management, you’d be hard-pressed to find a better example.

Finally, credit to former YC partner Anu Hariharan, who saw what made this team special very early and championed them from the start. She couldn’t have been more right.

Congratulations again to the Groww team.  It’s been our privilege to know and work with you, and we’re excited to continue to watch you grow(w)!

Today, BillionToOne goes public, becoming YC's fourth publicly traded biotech company. More importantly, they have built one of the most important genetic tests in the U.S. Today, 1 in 11 babies born in the US are tested with BillionToOne's fetal genetic test.

When we met Oguzhan and David, they were still PhD students. Oguzhan was taking CS183C, a course we were teaching at Stanford, and they decided to apply to YC even though, in 2017, YC did not yet have a track record of funding successful biotech companies.

Here's what they looked like in their YC application video.

While details of the business model have changed, the core idea for BillionToOne is the same as when they applied to YC. They believed it should be possible to create a prenatal genetic test that works by sequencing fragments of fetal DNA that naturally exist in the mother’s blood, and that this would someday be universally adopted. Before BillionToOne, most genetic abnormalities could only be detected via amniocentesis - an invasive procedure that is only used in high-risk pregnancies.

The idea is a fusion of biotech expertise with machine learning, which is required to make sense of the noisy data from sequencing free-floating fragments.

When they applied to YC, this was just an idea. But within 6 months, on only a very modest amount of funding, they had developed the actual test and proven its accuracy on test samples.

The reputation of biotech companies is that they are expensive, slow, and unpredictable. Somehow, BillionToOne has violated all of those stereotypes.

They went from starting the YC S17 batch to launching an approved, commercial genetic test in less than two years. And they did it on just a seed round's worth of capital.

Because biotech companies are doing novel and difficult scientific research, they understandably tend to run overtime and over budget. Not BillionToOne. From the day they launched the commercial test, they've grown revenue rapidly and predictably. We watched, amazed, as they consistently exceeded their revenue targets month after month after month.

There's a chapter in the BillionToOne story that shows a lot about the character and the execution skills of Oguzhan and David. When Covid struck, there was briefly a desperate shortage of diagnostic capacity to diagnose Covid cases. BillionToOne saw that they had the opportunity to help. In a flash, they repurposed their existing infrastructure and created one of the first FDA-cleared Covid tests. And somehow, they did all that on the side without ever missing their growth targets for their core business.

Today, BillionToOne is not just a prenatal genetic test. The same core technology for detecting free-floating DNA also works for detecting cancer via a blood test, known as a liquid biopsy. They launched an early version of this cancer test commercially in 2023, proving their ability to execute in two markets simultaneously.

Liquid biopsy tech is still in its infancy, though. It holds the promise of a blood test we all take regularly that will detect cancer early when it's most treatable. At scale, such a test could save millions of lives, and that is what BillionToOne is working towards.

BillionToOne shows what can happen when you combine an original scientific idea, a highly technical founding team, and exceptional execution. We're very proud to have been the first investor in the company and to support Oguzhan and David's deeply impactful work.

I'm excited to announce that nine exceptional founders are joining us as Visiting Partners at YC: Matt Riley, Harshita Arora, Grey Baker, Christopher Golda, Raphael Schaad, Christina Gilbert, Francois Chaubard, Vivian Shen, and James Evans.

Visiting Partners are former founders who are taking some time out before their next thing to help advise startups during the batch. They work closely with YC General Partners, sharing hard-won insights from building and scaling their own companies. Each of our new Visiting Partners brings a unique perspective—from design-led products and developer tools to AI infrastructure and edtech.

Matt Riley

Matt was the co-founder and CEO of Swiftype (YC W12), a search-as-a-service company acquired by Elastic in 2017. At Elastic, he was GVP & GM of the Search business unit, and led the product, engineering, design, and developer relations teams that brought Elasticsearch to market. He graduated from the University of Texas at Austin with BS and MS degrees in Electrical Engineering.

Harshita Arora

Harshita Arora grew up in India, where she discovered coding at 13 and dropped out of school at 15 to pursue it full-time. At 16, she built a crypto price tracking and portfolio management app that was featured by Apple and subsequently acquired. She then received an O-1 visa and moved to San Francisco, where she co-founded AtoB (YC S20), which builds financial infrastructure for the trucking and transportation industry. AtoB has raised over $125M in venture capital and serves 20,000+ fleets across the US. In her early 20s, Harshita is also the youngest ever visiting partner at YC.

Grey Baker

Grey was a co-founder of Pincites (S23) and of Dependabot, a developer tool used by over a million people that was acquired by GitHub in 2019. Previously, Grey was an early employee at GoCardless (YC S11) where he led product and engineering. He has an MPhil in Economics from the University of Cambridge, where he graduated top of his year.

Christopher Golda

Chris was the co-founder and CEO of BackType (YC S08), a data infrastructure & analytics company acquired by Twitter in 2011, where he subsequently launched and ran the Ad Center product, growing revenue to $1.4B. The distributed data processing work at BackType became the basis for the Lambda Architecture, and Chris helped open source Apache Storm, an early distributed real-time computation system. Post-Twitter, he has been working with founders to help them find customers and raise capital, participating in early-stage rounds of startups like Benchling, Coinbase, Stoke, and Supabase. Chris graduated from the University of Toronto and has a BASc in Electrical Engineering.

Raphael Schaad

Raphael is the founder and CEO of Cron (YC W20), a calendar product beloved for its craft and acquired by Notion in 2022. At Notion, he grew Calendar to millions of users and served as Head of Design for Growth and new products like Mail. Previously, he helped build Flipboard and iA Writer. Raphael holds a BS in Computer Science from Bern University of Applied Sciences and an MS in Media Arts and Sciences from MIT.

Christina Gilbert

Christina is the co-founder and former CEO of OneSchema (YC S21), the leading CSV ingestion platform trusted by thousands of developers to build AI-powered data pipelines. Under her leadership, OneSchema raised $10M from investors including General Catalyst, Sequoia's Alfred Lin, Elad Gil, and Contrary Capital, and was named a Forbes Cloud 100 rising star. Christina studied CS at Stanford, began her career as an Associate Product Manager at Google, and was recognized on the Forbes 30 Under 30 list in Enterprise Technology.

Francois Chaubard

Francois is an AI researcher and technology entrepreneur who founded Focal Systems (YC W16), the global market leader in AI applications for retail. He has built large-scale AI systems across retail, autonomous vehicles, and missile defense, and previously worked as a Computer Vision Researcher at Apple. At Stanford University, where he earned dual master's degrees in CS and EE, he created and taught some of the largest AI courses, including Machine Learning, Computer Vision, and Deep Learning for NLP. He lives in Woodside, California with his wife and two children.

Vivian Shen

Vivian is a founder, CEO, and angel investor who has built companies from zero to $50M+ in revenue and millions of users. She founded Acely, an AI tutoring platform that scaled from $0 to millions in ARR between 2024 and 2025, making it one of the fastest-growing AI businesses in education. Before Acely, she co-founded Juni Learning (YC W18), the online academy for kids' coding and math that helped define live, one-on-one online learning. Earlier in her career, Vivian worked as a software engineer at Google, a consultant at McKinsey, and led product at an AI commerce startup. She holds a B.S. in Computer Science with a minor in Creative Writing from Stanford University.

James Evans
James was the co-founder and CEO of Command AI (YC S20). Command built user assistance software, like in-site chat and messaging, and was acquired by Amplitude in October 2024. Prior to Command, James worked in private equity investing at Bain Capital and studied CS at Princeton.

We're looking forward to having Matt, Harshita, Grey, Chris, Raphael, Christina, Francois, Vivian, and James join the YC community in this new capacity. As YC alumni who've experienced the batch firsthand, they understand both its intensity and potential. Their willingness to invest time in the next generation of founders exemplifies what makes YC special—founders helping founders build the future.