YC Startup Directory

Brian Chesky

Marketplace

In 2008, before YC, Airbnb was broke. The fix wasn't a pivot — it was 800 boxes of cereal, $40,000 in revenue, and the willingness to look ridiculous in front of investors.

Drew Houston

Cloud Storage

Drew Houston couldn't get product/market signal because nobody understood what Dropbox did. So in 2008 he made a screencast aimed at one community — and woke up with 70,000 new users.

Patrick Collison

Fintech

In 2010, accepting a payment online required a merchant account, a payment gateway, weeks of paperwork, and PCI compliance. The Collison brothers shipped a competitor that worked in seven lines of curl.

Michael Litt

Other

Two engineering students in Canada — one designing toilets, one sitting idle at BlackBerry — used a day-trading windfall to buy a house, build a video company nobody asked for, and accidentally discovered the real product while trying to solve their clients' confusion. Then they drove 1,200 miles with a car covered in stickers to crash a conference and corner a keynote speaker.

Ryan Carson

Other

Ryan Carson watched developers graduate from college without knowing how to code for real jobs — so he spent 6 years building a blog audience first, then launched a product to that audience and hit $1.7M revenue in under 12 months, teaching over a million people to code before anyone in Silicon Valley thought online education could work.

Jessica Mah

Other

A 19-year-old CS student who had never held a real job, knew nothing about accounting, and dropped out of high school at 15 — built the "Mint.com for business," nearly destroyed it through arrogance, then pivoted her way to 2,686% revenue growth and the cover of Inc. magazine.

Lee C. Lin

Other

Two MIT-trained quants looked at Craigslist — the most-visited, least-innovated website in America — and decided the apartment hunt didn't need disruption with venture-scale fireworks. It needed a better ranking algorithm, patient bootstrapping, and fifteen years of quietly outlasting better-funded competitors.

Laura Valverde García

Other

A self-taught Spanish developer from Seville moved to San Francisco with a brilliant idea at exactly the right moment — got into YC, hit real traction, mentored by legends — and then watched everything collapse when Facebook changed the rules overnight. What she built next was smarter, and what she learned is priceless.

Corey Pierson

Other

A guy who built a million-dollar sporting goods company and walked away with nothing, and a Wharton MBA studying Bayesian probability models, figured out that retailers were measuring customer value completely wrong — then turned an academic formula into a $31.8M-funded product that ended up being acquired by one of the most sophisticated customer data platforms in the world.

Yuri Sagalov

Other

A Russian-born, Canadian-raised grad student who had immigrated twice and rebuilt twice, left a Masters degree mid-program to turn a distributed systems research project into the "Dropbox that lives behind your own firewall" — earning Paul Graham's highest praise and the trust of Fortune 500 security teams who couldn't store a single byte outside their own servers.

Justin Santa Barbara

Other

A Cambridge-educated engineer working odd jobs in London spotted a problem that the entire cloud industry would eventually validate — databases were still being run like it was 1995 — got into YC in 2008, built the world's first relational Database-as-a-Service, and then watched Amazon build the same thing six months later. FathomDB's story is not one of failure — it's one of being **exactly right, at exactly the wrong time, against exactly the wrong competitor.**

James Lindenbaum

Developer Tools

Three developers at a boring consulting shop in Los Angeles fell in love with Ruby, went to a conference that felt like a religious awakening, and built a product nobody wanted — until they pivoted to what everyone was secretly already using them for. The result: a $212M exit on $13M raised, and a deployment command — `git push heroku main` — that a generation of developers will never forget.

Jonathan Deutsch

Other

Two senior Apple engineers, with ringside seats to the death of Flash and the birth of HTML5, left the most coveted jobs in tech to build the tool that didn't exist yet — a designer-friendly way to animate the modern web — and then did something almost nobody in Silicon Valley does: they said no to all the money, stayed small, and won anyway.

Adam Goldstein

Other

A fresh MIT grad convinced the co-founder of Reddit to bet three months on a travel search idea — they launched in 90 days, got CNN coverage within 24 hours, raised $55M, sold to SAP, and watched it get shut down. What Hipmunk teaches you about building fast, designing brilliantly, and losing control of what you built is worth more than most success stories.

Ben Congleton

Other

A PhD student who once sold pencils in elementary school applied to YC during the worst recession in a generation — and was offered the option to *not* come, because YC itself wasn't sure anyone could raise money. He came anyway, changed his company's name twice, and built a profitable SaaS business on $85,000 total outside capital.

Weiting Liu

Other

A Taiwanese immigrant and Stanford engineer watched Mark Zuckerberg speak and thought, *"It's not impossible to build something big right after school"* — then spent the next two years trying to do exactly that, turning stock market communities into a social graph before anyone called it fintech.

Jeff Widman

Other

A former TechCrunch intern and a Seth Godin apprentice discovered a stat so shocking it went viral across the marketing world — only 3–7% of a brand's Facebook fans ever see their posts — then built the tool that proved it, sold it to YouTube and MTV, and got acquired in under 3 years.

Alexander Wissner-Gross

Other

A Harvard physicist who triple-majored at MIT — the last student ever permitted to do so — turned a PhD thesis on the energy cost of computing into a web analytics company that made the carbon footprint of websites measurable, actionable, and eventually worth acquiring. He did it before "sustainability" was a tech buzzword, before ESG was a board agenda, and before anyone outside of academia believed the internet had a climate problem.

Umur Cubukcu (CEO), Ozgun Erdogan (CTO), Sumedh Pathak (VP Engineering)

Other

Three Stanford-trained engineers left comfortable jobs at Amazon and BCG, moved to Istanbul to build in the quiet, and bet everything on a contrarian belief the entire industry had abandoned — that relational databases could scale — and eight years later, Microsoft proved them right.

Justin Kan, Emmett Shear, Michael Seibel, Kyle Vogt

Other

Justin Kan and Emmett Shear failed twice, sold their second company for pennies on eBay, strapped a webcam to Justin's head to prove live streaming was possible — and then watched their gaming vertical quietly overtake everything they had built, becoming a $970 million company that nobody thought was a real business.

Brett Huneycutt, Jonathan Good & Rudy Adler

Other

Three high-achieving professionals — two McKinsey consultants and an ad agency creative — each quietly lost someone they loved, found the internet's memorial options embarrassing and cold, then quit their prestigious jobs on the same week to fly to San Francisco and build something more worthy of the people they'd lost.

Matt MacInnis (CEO), Josh Forman (VP Product), Robert Cromwell (VP Engineering)

Other

A Canadian Apple insider quit his dream job on a Friday, filed incorporation papers by Monday, then spent nearly a decade learning the hardest lesson in startups — that being right about the technology and wrong about the customer are not mutually exclusive.

Darius "Bubs" Monsef IV (CEO), Aaron Epstein, Chris Williams (CTO)

Other

Three founders who thought they were "too old" and "not the right demo" for Y Combinator almost talked themselves out of applying — then got in with a color-palette community, were told by Paul Graham they could "change how the world looks," pivoted twice inside the batch, and sold the resulting marketplace for eight figures fifteen months after launch.

Kenshi Arasaki, Wilkins Chung, Eric Diep

Other

Three Canadian engineers quit Amazon, got into YC with a chat app, watched it fail to take off — then noticed something unexpected in their own data: people were using their chat rooms to form war clans. They ignored everything they'd built and followed the community. That pivot became one of Canada's most profitable mobile game studios, built entirely without venture capital.

Zak Homuth (CEO), Stephen Hamer (CTO), Michael Woodworth

Other

Three engineers from Waterloo looked at a $4 billion EDA software industry that hadn't changed meaningfully in 30 years, asked why hardware design still felt like the 1990s, and built the "GitHub for hardware" — then had to pivot their entire business model three years before anyone would pay them for it.

Kevin Gao (CEO) & Min Ming Lo (Co-founder)

Other

A McKinsey consultant who was too lazy to answer the same emails twice accidentally built a $100K side business from a 90-page eBook — then parlayed that proof into a YC-backed publishing platform that raised $1.2M from Andreessen Horowitz, only to discover that what works at one book rarely scales to thousands.

Darshan Shankar (CEO), Sridatta Thatipamala, Eric Zhang

Other

Three engineering students at UC Berkeley walked into YC with a shopping app, turned down a $1 million investment on Paul Graham's advice, pivoted to real-time messaging infrastructure, raised $1.4M from a16z — and still shut down. Then the founder built one of the world's most popular VR platforms. This is the story YC doesn't put on its homepage — and the one aspiring founders need to read most.

Joey Flores (CEO), Yotam Rosenbaum (Co-founder), Benjamin Bryant (VP Technology)

Other

A slam poet with a $60M marketing career and his jazz drummer bandmate sat in L.A. traffic, asked one question — "What if music promotion worked like Google AdWords?" — and turned that roadside idea into a YC-backed company that proved you don't need to be a Silicon Valley insider to build something the world's best accelerator will fund.

Elizabeth Iorns

Other

A breast cancer researcher in Miami couldn't find a lab to run a single experiment for her — so she built the platform that eventually became the Amazon of scientific R&D, trusted by 8 of the world's top 10 pharmaceutical companies.

Gee-Hwan Chuang

Other

Two Cornell engineering grads with zero working code walked into their YC interview running their demo over a flaky Skype call from Taiwan — and got accepted anyway, because what they were really selling wasn't a product, it was a conviction about why people hoard useless stuff instead of trading it away.

David Zhao

Other

Three engineers from Microsoft and Amazon saw the same broken problem every day at their desk jobs — carrying content between devices was painful — and instead of complaining about it, they quit, applied to YC, pivoted once, and built the technology that powered HP's entire netbook line before Dropbox was even a household name.

Harj Taggar

Other

Four young founders — two Oxford law students and two Irish teenage prodigies — walked into YC with the wrong idea, pivoted within three weeks, built something real, and sold it for $5 million before any of them turned 25. One of them became CEO of Stripe. One became a YC Managing Partner. One built a $450M company. One launched a VC fund. Auctomatic wasn't the destination — it was the launchpad.

Rune Sørensen

Other

Three Danish developers flew to Silicon Valley, got into YC, built the right product for the right underserved community — and still couldn't win. AppHarbor is the story every aspiring founder needs to read: not because it failed, but because it got so much right and still didn't make it.

Jeff Hunter

Other

Two Apple engineers, living as roommates, kept buying duplicate groceries because their lists never synced — so they built the fix themselves, shipped it as a side feature, watched it explode past their main product, and quietly turned a $120K YC cheque into a $2M/year business with a team of two.

Steve Huffman

Social

Two college seniors who wanted to avoid real jobs pitched an idea that got rejected — but got accepted anyway — and were handed a completely different idea by their investor, which they built in three weeks, seeded with fake accounts, and grew into the front page of the internet.

Joseph Walla

Other

A political science graduate with no tech background posted an idea on Hacker News, found a co-founder in 48 hours, got into YC with a fax company — and accidentally discovered a $230 million business hiding inside it.

Nick Baum

Other

Two Dartmouth graduates — a quant from Wall Street and a finance analyst — went through YC with a consumer gifting idea that nobody understood, quietly became profitable while the startup world ignored them, spotted a hidden B2B signal in their own data eight years later, and built a $100M+ revenue machine without taking a single dollar of venture capital.

Drew Harry

Other

Drew Harry built a real-time online whiteboard in 2006 that worked — got into YC, got press, got users — and still shut down four years later. The lesson isn't about the product. It's about building something people admire vs. building something people pay for.

Jon Wheatley

Other

A laid-off British web developer, broke and living in his mom's closet, turned a late-night idea into a 6-million-visitor-a-month phenomenon backed by Sequoia — then watched it get acqui-hired and shut down three years later, a cautionary tale every aspiring founder needs alongside the victory stories.

Leah Culver

Other

A celebrated developer, fresh off her first acquisition, built a group chat product for everyone — and discovered too late that "for everyone" is a product for no one.

Scott Wheeler

Other

Rejected by YC without even an interview, Scott Wheeler's first reaction was "Paul Graham could go to hell — I'll show him." A year of grinding later, with the exact same idea and the exact same team, he got in — because the company, not the application, had become undeniable.

Solomon Hykes

Other

A French coder with no Silicon Valley connections, no investors, and no business plan — rejected by YC once — somehow got in at the last minute, built the wrong company for three years, and then bet everything on an open source side project that rewrote how the entire world ships software.

Sean Creeley

Other

Two founders in Boston — far from the Silicon Valley spotlight — noticed that "embedding a link" on the web was a fragmented mess, built a meta-layer on an obscure protocol nobody had taken seriously, and quietly became the embedding engine running underneath LinkedIn, Reddit, and The New York Times for six years.

Suhail Doshi

Other

A 19-year-old college junior who thought Google Analytics was philosophically wrong dropped out with one classmate, nearly ran out of money twice, and built the company that taught the software industry to stop counting pageviews and start counting people.

Sachin Agarwal

Other

Three Stanford engineers built the world's simplest blogging platform — post anything just by sending an email — grew it to 15 million users, then watched it unravel the moment they stopped trusting simplicity. One founder went on to run Y Combinator. The story of Posterous is equal parts inspiration and cautionary tale.

Chris Smoak

Other

A Carnegie Mellon engineer in 2006 saw that people were passionate about their personal style but had nowhere online to share it — built a fashion social network three years before Instagram existed, got into YC, couldn't crack user retention, pivoted twice, shut it down, and used everything he learned to do YC two more times with bigger swings.

Zack Garbow

Other

Two engineers built a browser extension to socialize the web in 2008, watched it quietly die, and then Dave Fowler took every lesson from that failure straight into YC a second time — where he built Chartio, made Forbes 30 Under 30 twice, and eventually sold to Atlassian.

Jon Dahl

Other

A philosophy grad student who taught himself to code teamed up with two engineers to kill an expensive, hardware-bound problem — video encoding — and turned it into a simple API, then sold the company just two years later, before raising a single dollar of venture money for the round that mattered.

Wayne Crosby

Other

Two PhD engineers — one applying to YC the same night his wife told him she was pregnant — built a browser-based PowerPoint killer in a few months, got acquired by Google, and accidentally created the tool that over a billion people now use to present their ideas to the world.

Adam Smith

Other

Two engineers — one from MIT, one from Penn State — met at a Washington D.C. internship, recognised that email was a broken mess of buried relationships, and built a product from a dorm room that Bill Gates personally demoed at a Microsoft conference. Then they turned down $20M from that same Microsoft — and eventually sold for $60M+ to Yahoo instead.

Philip Yuen

Other

A Paul Graham essay kept a Microsoft engineer up at night, pushed him to quit his stable job, fly across the country to a lecture, get into YC's first-ever batch with the wrong idea — then pivot to the right one mid-batch, get acquired by Amazon within a year, and plant the seed for what eventually became every P2P payment app you use today.

Ivan Kirigin

Other

A robotics engineer and a UX designer — married, bold, and early — got into one of YC's smallest-ever batches to solve internet tipping before the internet was ready for it. They were 18 months too early, ran out of runway, and still built one of the most valuable founder careers in Silicon Valley from the wreckage.

Amir Nathoo

Other

Three Cambridge and MIT-educated engineers left corporate jobs at IBM to build the simplest way for web developers to create native mobile apps — got into YC, raised money, grew fast, and then watched the entire HTML5-vs-native debate kill their market before they could outlast it.

Joshua Wilson

Other

Two MIT undergrads on leave of absence got into YC in 2007, raised seed funding from the legendary Ron Conway, and built a technically prescient mobile infrastructure product — one year before the iPhone App Store made their entire approach obsolete overnight.

Jamie Cameron

Other

Two open-source veterans who had been quietly building the world's most-downloaded Linux admin tool for a decade realised they'd given away a million-dollar product for free — and YC gave them the framework to finally charge for it.

David Rusenko

Other

Three college kids built a website builder as a class project, applied to YC with one hour left before the deadline, got told their idea was "the worst ever heard" at their first public demo — and spent the next 12 years quietly proving everyone wrong on the way to a $365 million exit.

Kevin Hale

Other

Three friends from Tampa who hated building forms were told by Paul Graham to build a form product — and almost said no. They said yes, refused VC money, never grew beyond 10 people, sent handwritten thank-you cards to every paying customer, and sold for $35 million. The most unsexy startup in YC history is also one of its most instructive.

Beau Hartshorne

Other

Two developers in one of YC's very first cohorts built a browser-based photo editor years before Canva, Figma, or even the iPhone existed — and proved that being early and being right are two very different things.

Ian Hogarth

Other

A literature graduate, a Cambridge-trained engineer, and a best friend from university — none of them startup people — solved a problem so personal and obvious that they almost talked themselves out of applying. Songkick became the world's second-largest concert platform by refusing to outsmart itself: they just built what one of them desperately wished existed.

Dave Brushinski

Other

Dave Brushinski built the world's first browser-based Photoshop-like editor in 2006 — layers, brushes, effects, the whole thing — before anyone else had proved it was possible. He got into YC, got press, got users. Then the market caught up, better-funded competitors arrived, Flash died, and Splashup quietly closed. The idea was right. Almost everything else was a lesson.

Jesse Tov (+ co-founders

Other

Jesse Tov joined the first-ever YC batch almost by accident, pivoted from résumés to online dating on Paul Graham's suggestion, and shut down five months later — then went on to teach computer science at Harvard and Northwestern. His story is proof that YC success isn't always a unicorn. Sometimes, it's the clarity to know what you're not meant to build.

Hovig Bayandorian

Other

In 2006, one founder built a tool that let strangers chat when they landed on the same website — a concept so ahead of its time that the infrastructure, smartphones, and social norms to support it wouldn't exist for another decade. Talkito didn't fail because the idea was bad. It may have failed because the world wasn't ready yet.

Sumon Sadhu

Other

A Oxford-educated biochemist dropped his PhD, got headhunted by Paul Graham into one of the earliest YC batches, built the world's first IP-targeted developer job ad network, made $30K before Demo Day — and then shut it all down two years later because he was five years too early for the market he was trying to create.

Trip Adler

Other

Three Harvard students applied to YC with an idea that Paul Graham told them would never work — then spent six months in "pivot hell" inside the inaugural YC batch before stumbling onto an idea inspired by a doctor's frustration with academic publishing. What they built became one of the world's largest digital libraries.

Charles Forman

Other

A twenty-something from Chicago who built a dating site as a joke, accidentally invented "gamification," spent six brutal years making 35 games nobody cared about, burned out and left with $1,700 to his name — and then got a phone call telling him he was about to become a multi-millionaire.

Ryan Junee

Other

Three Australians with engineering degrees, no prior exits, and no Silicon Valley network walked into YC with a single powerful insight — online video is a static, one-way broadcast when it could be a living, interactive medium — and sold that insight to Google less than a year later.

Blake Ross

Other

The teenager who built Firefox while still in high school didn't wait for the world's permission — he just kept shipping. Parakey never launched publicly, was acquired before most people knew it existed, and became the foundation that shaped Facebook's product team for the next decade.

Brian Bakerman

Other

Two Carnegie Mellon engineering students noticed that California had quietly passed laws making it dramatically easier to build homes in backyards — and decided to build a factory to exploit that window at scale. They got into YC, raised funding, built a real factory in Oakland, reached $10M+ in contracted revenue — and then ran out of money before they could reach profitability.

Jeff Vyduna

Other

Three Deloitte consultants were so tired of watching audiences zone out during their own presentations that they built a text-message voting tool to keep people awake — then discovered they'd accidentally created the product that would kill a $15,000-per-unit hardware industry.

Joe Wong

Other

Three founders walked into YC with a web desktop OS nobody wanted, pivoted mid-stride into wedding planning, sold the company twice — and then did it all over again a decade later with Zeus Living. This is a story about the power of the pivot, the courage to abandon your original idea, and what happens when a real couple builds a product for real couples.

Tony Wright

Other

While every other startup was chasing hockey-stick metrics, three Seattle founders quietly built a product on evenings and weekends to answer one brutally honest question: "Where does all my time actually go?" — and in doing so, created one of the most enduring productivity tools the internet has ever seen.

Andres Morey

Other

Three physics PhD students were so frustrated searching for electronic components for their lab experiments that they built a search engine for it — dropped out of grad school, nearly went broke during the 2008 financial crisis, refused to quit, and turned a boring niche into a half-million-user platform that got acquired eight years later.

Patrick Swieskowski

Other

Two open-source hackers were so fed up with the ritual humiliation of reinstalling Windows — the toolbar junk, the "click next 47 times" installers, the adware hiding inside free software downloads — that they built the cure. Fifteen years later, it still runs with 2 people and serves NASA.

Ben Silbermann

Other

A doctor's son from Iowa who was never supposed to be a founder, never learned to code, and watched his first YC company quietly die — then used everything he learned from that failure to build one of the most-used websites on the internet.

Radley Marx

Other

Two designers built the most loved online mixtape of 2008, got into YC, grew a passionate user base — and then shut down because they were too honest to pretend the music industry would leave them alone.

Russell d'Sa — Founder

Other

Russ d'Sa built the first webcam-based social meeting site in 2007, watched it fail when the world wasn't ready — then spent 15 years in the wilderness of Twitter, HR software, mobile streaming, and pandemic pivots — before finally building the infrastructure that made his original vision possible, and landing OpenAI as his most important customer.

Gabriel "Gabe" Leydon

Other

A man who started his company while collecting unemployment benefits — and who came from the dying world of coin-op arcade machines — looked at the iPhone and saw something everyone else missed: not a phone, not a gaming device, but a virtual supermarket in everyone's pocket. He was right, and it made him a billionaire.

Sam Altman + Nick Sivo

Other

Sam Altman was 19, a Stanford dropout, and building a location-sharing app in 2005 — two years before the iPhone existed. Loopt never became the billion-dollar company he imagined, but it got him into the first YC batch ever, taught him how the best founders think, and launched one of the most consequential careers in the history of Silicon Valley.

Gabe Smedresman

Other

A Yale student accidentally built a game so addictive that 25% of his entire campus played it — then turned that accident into a YC-backed startup, only to discover that virality and a business are two very different things.

Justin Kan

Other

Kiko failed in 12 months, got killed by Google, and was sold on eBay for $258,100 — and it's one of the most important startup stories in YC's entire history, because the two founders who built it went on to create Twitch, which sold to Amazon for $970 million. This is the story of what a "failed" startup actually looks like — and why failure is often just a slow-burning launchpad.

Dane Atkinson

Other

A man who had already been CEO of six companies — including Squarespace — walked into YC at 46 with a gut instinct about coffee shops, watched COVID erase every dollar of revenue he had, then rebuilt from zero to $150M in two years by doing the one thing every software founder avoids: delivering physical goods overnight.

AJ Asver

Other

Two immigrant engineers — one from Sri Lanka via MIT, one from Oxford — built one of the world's first real-time search engines, got into YC when almost no one understood what real-time search meant, pivoted hard when the market shifted under them, and ended up inside Google helping build the future of social. It wasn't a straight line. It was a masterclass in staying technically relevant while the world caught up.

Jorge Ortiz

Other

A Stanford-trained engineer looked at the STEM hiring market in 2007, saw a broken connection between brilliant talent and the companies that needed them most, got accepted into YC to fix it — and in doing so, built the skills and credibility that launched a career at three of Silicon Valley's most important companies.

Gautam Jayaraman

Other

Four college friends with a shared love of music and a question — "Why isn't there a YouTube for audio?" — built one of YC's earliest consumer products: a browser-based remix platform that grew to 75,000 members, ran remix contests with major artists, and then quietly shut down — teaching its founders lessons that funded everything they built next.

Michael Hartl

Other

Two Harvard-educated physicists with PhDs built the "WordPress for social networks" in Ruby on Rails, got into YC, became one of GitHub's most-forked repositories, nearly raised a significant funding round — and then watched the 2008 financial crisis kill the deal in October. The company shut down. The founder wrote a tutorial instead. That tutorial made $750,000 and became the most widely read Rails resource in the world.

Aaron Swartz

Other

The 18-year-old who co-authored RSS, dropped out of Stanford, and walked into Y Combinator's very first-ever batch with an idea that never quite found its market — and in failing to scale Infogami, accidentally gave the internet Reddit, web.py, and Open Library.

Shadab Farooqui

Other

A 25-year-old from Bombay who never planned to be a founder accidentally built one of the internet's first social music platforms, got into YC, scaled to 5 million users — then watched the music industry kill everything he built.

Gustaf Alstromer

Other

A team of Swedish founders shipped the right product two years too early, built 1 million users without cracking growth, got acquired quietly — and then the CEO spent the next decade becoming one of the world's foremost experts on the exact problem that killed his company: distribution.

Phillip Wang

Other

A team of recent college graduates tried six different product ideas — wristwatches, robots, tablet apps, VR — failed at all of them, pivoted when a pandemic hit, and accidentally built the most human-feeling video platform on the internet by making it look like a video game.

Shashank Pandit

Other

Three Indian PhD students at Carnegie Mellon built a shared-expense tracker out of sheer frustration with IOUs on a refrigerator — got into YC, grew to 100,000 users, watched both co-founders leave for Facebook, and then one of them quietly rebuilt it alone into a profitable, privacy-first personal finance tool still running 18 years later.

Rob Fitzpatrick

Other

Two college friends pitched a video game studio to YC, pivoted the idea mid-interview when the partners tore their business plan apart, got funded anyway, built an animation platform used by Sony and Aardman, raised from top-tier investors — and still shut down. Then Rob Fitzpatrick turned the entire painful experience into The Mom Test, a book that has saved thousands of startups from making the exact mistakes he made.

Cole Rise

Other

Cole Rise built a mobile location-sharing app in 2006 — before the iPhone existed, before the App Store existed, before Instagram was a thought — and though Flagr didn't survive, the creative instincts he honed there led directly to designing Instagram's original filters and icon, two company acquisitions (by Apple and Microsoft), and a career that quietly shaped how a generation sees the world through a phone screen.

Daniel Ha

Other

Two college friends, bored in computer science classes and building side projects for fun, accidentally created the internet's default comment system — not by chasing a big idea, but by following the one small feature that people actually showed up to use.

Savraj Singh

Other

Three Microsoft engineers left their stable jobs, got into YC Summer 2007 alongside Dropbox and Arash Ferdowsi, built a real product that actual beauty bloggers loved — then ignored the most important warning Paul Graham ever gave them, and learned the hard way that being technical is not enough.

Paul Mikesell

Other

A serial founder who already built and IPO'd one $2.5 billion company walked away from a comfortable exit, saw the exact same scaling problem destroying the next wave of the internet, and spent 12 years quietly building the database that the world's fastest-growing web companies would depend on — before handing it off to the open-source community.

Michael Miller

Other

Three MIT physicists were moving petabytes of data from the world's largest physics experiment and couldn't find a single tool that worked at that scale. So they built one — and accidentally created the cloud database infrastructure that IBM eventually paid to own.

Peter Nixey

Other

Two British engineers in one of the first five YC cohorts saw that internet login was broken, built an elegant fix on top of an open standard — and then watched the standard lose to Facebook and Google. What they built was the right product. What they learned was priceless.

Christopher Golda

Other

Two Canadian engineers from Toronto — who had already built and failed with one startup — walked into YC Summer 2008 with a simple idea about blog comments, and walked out having quietly invented the infrastructure that powers real-time social data analytics at Twitter scale.

Aaron Iba

Other

Three ex-Google engineers left stable, prestigious jobs to build a developer platform nobody used — then accidentally invented real-time collaborative editing on a Friday afternoon, watched that side project become the real company, and got acquired by Google two years later. The thing they built to demo the product they failed at became one of the most influential pieces of software infrastructure in the modern internet.

Sachin Rekhi

Other

Paul Graham told them he hated their idea — then funded them anyway, on one condition: come up with a new one. What happened next is one of YC's clearest lessons about what actually gets you in: the team, not the idea.

Francisco Tolmasky

Other

Three USC college friends — two of whom had built parts of the original iPhone — got so frustrated with how terrible web development was that they secretly built a better version of Apple's own desktop toolkit for the web, launched it as open source, and were acquired by Motorola for $20 million just two years later.

Matt Maroon

Other

A professional poker player from Akron, Ohio walked into Y Combinator with a fantasy sports gambling idea, got funded, watched that idea fail — then accidentally built the largest virtual universe on Facebook by launching a side project to promote a product nobody wanted.

Patrick Swieskowski

Other

Two solo founders walked into YC W08 with two different ideas, met each other, killed both ideas, failed at an app store, and accidentally built one of the most reliable and beloved utility tools on the internet — with a team of just two people, forever.

Ethan Herdrick

Other

Two programmers with a genuinely interesting idea — "Wikipedia, but for every person on earth, not just famous ones" — got into YC, built the product, launched it publicly, and watched it die in silence five months later. Not because the idea was wrong, but because they launched a community product with nobody in the community.

Altay Guvench

Other

Audiobeta failed. And that is precisely why this story belongs in every aspiring founder's reading list. Two of its founders went on to build a $12 billion company and a second YC-funded startup — proof that the most important thing a failed startup can give you is not a return on investment, but a return on learning.

Justin Kan, Emmett Shear, Michael Seibel, Kyle Vogt

Live Video

Justin.tv was a YC company that flatlined. They quietly built a 'gaming' subdirectory that ate the whole company.

Brian Armstrong, Fred Ehrsam

Fintech / Crypto

Coinbase nearly didn't make it into YC S12 — Brian Armstrong's original co-founder was rejected mid-interview. Brian went solo into the batch.

Henrique Dubugras, Pedro Franceschi

Fintech

Henrique and Pedro killed their VR startup inside YC. They pivoted to corporate cards mid-batch.

Apoorva Mehta

Marketplace

Apoorva failed at 20 startups before Instacart. He applied to YC S12 after the deadline. He got in by delivering PG a six-pack via his own app.

Wade Foster, Bryan Helmig, Mike Knoop

SaaS / Automation

Zapier's first YC application was rejected. They shipped a working product, applied again to S12 with paying users, and got in.

Peter Reinhardt, Calvin French-Owen, Ilya Volodarsky, Ian Storm Taylor

Developer Tools

Segment entered YC S11 with a classroom analytics tool. It failed. They open-sourced a tiny internal library called analytics.js — that became the company.

Tony Xu, Stanley Tang, Andy Fang, Evan Moore

Marketplace

DoorDash entered a 'finished' market in 2013 — every food delivery thesis was already funded. They drove the deliveries themselves.

Joshua Reeves, Tomer London, Edward Kim

Fintech / HR

Gusto entered YC W12 as ZenPayroll. Every investor told them payroll was already won by ADP. They went after it anyway.

Harshil Mathur, Shashank Kumar

Fintech

Razorpay's founders pitched to 100+ Indian banks before one said yes. They got into YC W15 with the partnership still unsigned.

Kyle Vogt, Daniel Kan

Autonomous Vehicles

Cruise entered YC W14 trying to retrofit autonomy onto regular cars. The industry called it impossible. GM bought them 2 years later.

Ryan Petersen

Logistics

Flexport pitched 'software for freight forwarders' at YC W14. Every logistics insider said the industry would never digitize. Ryan kept going.

Dan Siroker, Pete Koomen

Marketing / SaaS

Optimizely's founders entered YC W10 with an education game. They killed it mid-batch and pivoted to A/B testing — the tool they'd built for the Obama 2008 campaign.