How Two Developers Got Into Y Combinator
It was early 2024, and I was sitting in our co-working space in Barcelona...
It was early 2024, and I was sitting in our co-working space in Barcelona, staring at my inbox. Morning light came through the window. My coffee had gone cold, but I kept refreshing the page anyway, even though I already knew what I’d find.
Nothing. Zero responses – not from yesterday, not from the day before, not from the entire week before that. We had sent hundreds of cold emails over the past month. Not a single person had replied.
My co-founder Veronica and I had just won a hackathon a few weeks earlier with Lingo.dev, a localization tool we’d built for developers like ourselves. About twenty people were actually using it, and some of them really loved what we’d made. They’d message us saying how much time it saved them, how they wished they’d had something like this years ago. That felt good. But we had no idea if any of this could become a real business – something that could pay our rent, something we could work on for the next ten years.
I remember one morning around that time, walking to a café near our place while the streets were still quiet. I was thinking about how we’d spent the last five years following Y Combinator from afar – the startup accelerator behind Airbnb, Stripe, Dropbox – reading Paul Graham’s essays, watching the YouTube lessons and podcasts. We’d always said it would be cool to apply someday. But “someday” had always felt far away, like something that happened to other people.
That morning, something shifted. We realized we could build almost anything when it came to software – we’d proven that to ourselves already. But what we wanted now was different. We wanted to build something that mattered, something that could grow and help thousands of developers, not just twenty. And if we were serious about that, we needed to figure out whether Lingo.dev had real potential or whether we were just two builders tinkering in Spain.
So we decided to learn how to sell.
The Book
I knew there was a book called “Founding Sales” by Peter Kazanjy. I’d seen it recommended in YC resources and I wanted a physical copy, something I could mark up and carry around and leave open on my desk. But when I tried to order it on Amazon, I discovered that Amazon Spain is basically a different Amazon. The book wasn’t available. I tried the US site, but couldn’t get it shipped to a Spanish address.
So I posted on Twitter:
A stranger replied – Brad van Leeuwen, co-founder of Cledara. He was flying to Barcelona the following week for a business trip. He offered to buy a copy and bring it with him.
A week later, he handed me the book at a coworking space on La Diagonal. I still think about that sometimes, how a random act of kindness from someone I’d never met set the whole thing in motion.
We read it together, Veronica and I, passing it back and forth and underlining passages. We learned about cold outreach, how to structure emails, follow-up cadences. For the first time, we felt like we had a playbook.
Then we started sending emails. Lots of them – to CTOs, engineering managers, anyone whose company might need localization. We crafted what we thought were compelling messages, personalized each one, followed up exactly when the book said to follow up.
Nothing happened. Not a single demo booked. Not even a polite “not interested.” Just silence, day after day, refresh after refresh.
That was the lowest point.
We started to wonder if maybe we just weren’t cut out for this. We were developers, not salespeople. Maybe there was some secret template that real founders used, some magic formula we didn’t know about. So we tracked down a few founders we’d met at events and asked if they’d share their outreach emails with us. They were generous – sent us their actual templates, the ones that had worked for them.
And you know what? The emails were good. Definitely more polished than ours. But they weren’t wildly different. The structure was similar, the tone was similar.
That’s when it hit us. The problem wasn’t the format of our emails. The problem was what we were saying. We were talking about features, about our technology, about what we thought was impressive. But we weren’t talking about what our potential customers actually cared about. We didn’t know the words they used to describe their problems. We didn’t know what kept them up at night. We were guessing, and we were guessing wrong.
Forty Conversations
So we changed our approach completely. Instead of trying to sell, we started doing research.
We reached out to developers and engineering leads with a different message: “We’re exploring how teams handle localization. Would you be open to a 30-minute conversation? No pitch, just trying to learn.” No company name, no product demo. Just genuine curiosity.
And people said yes.
Over the next two months, we did somewhere between forty and fifty of these conversations, each one following the same format: How do you handle localization today? What’s the most frustrating part? If you could wave a magic wand and have the perfect solution, what would it look like?
At first the answers seemed scattered – everyone had slightly different setups, different tools, different complaints. But after about twenty conversations, a pattern started to emerge. After forty, it was undeniable. People were describing the same problems using the same words. The same phrases kept coming up, almost verbatim: “Translation delays are killing our release cycles.” “We waste hours on string management.” “The handoff to translators is a mess.”
It was like they were all reading from the same script, except they weren’t. They’d never talked to each other. These were just the words that naturally came to mind when developers thought about this problem.
We rewrote everything – our landing page, our emails, our pitch – using the exact language we’d heard in those conversations. We stopped describing what our tool did and started describing the pain it solved, in words our customers would recognize as their own.
Within a week, we booked our first real demos.
The lesson wasn’t really about sales. It was about sequence. When you’re facing a problem that feels impossibly hard, the instinct is to charge straight at it. But sometimes the real problem is that you’re trying to solve step two before you’ve solved step one – and step one might require a completely different kind of effort than what you were planning.
We thought we had a sales problem. We actually had a research problem. Once we solved that, the sales started to happen on their own.
First Rejection
A few months later, in mid-2024, we submitted our first application to Y Combinator. I remember clicking the submit button and feeling a mix of hope and skepticism. We’d talked about YC for years, and now we were actually applying. It felt surreal.
A few weeks later, the email came. We’d been rejected.
In hindsight, the application was pretty bad. We didn’t include a demo video – our logic was that nobody wants to watch a terminal app, just code scrolling by, commands being typed. We thought it would bore the reviewers. That was a mistake. What we didn’t realize is that YC applications get routed to partners who understand the domain. If someone reviews developer tools all the time, they’re not going to be bored by a terminal. They’re going to appreciate it. By skipping the demo, we made it harder for them to see what we’d actually built.
We also had almost no traction – a handful of users, no revenue, no clear proof that anyone would pay.
One thing I learned later is that YC sends different types of rejection emails. There’s the standard rejection, then “rejected but top 10%,” then “top 5%,” then people who get interviews and still get rejected, and finally people who get in. We were in the top 10%. Not great, but not nothing.
We made a decision that night: we wouldn’t judge ourselves based on one application. We’d apply again in six months and use the difference between the two applications as a signal. If we’d made real progress – more users, more revenue, a better product – that would tell us we were on the right track. If nothing had changed, we’d have to rethink everything.
So we went back to work.
We kept building, kept talking to users. We started getting paying customers – not many, but real ones, people who pulled out their credit cards and used the product every day. One of them was Cal.com, the open-source scheduling tool. Working with them was intense. They’d ask for a feature and we wouldn’t just add it to the roadmap – we’d sit down, build it, push it to production, update the docs, and reply in the same thread: “Done. Here’s how to use it.” Sometimes in an hour, sometimes two.
I remember one night we were on our way home, exhausted. It was probably 10 PM. Then a message came in: our users needed something. We looked at each other, called an Uber, and went back to the office. Shipped the feature at 1 AM.
It was the best kind of exhaustion – the kind where you’re tired but completely alive, because you know what you’re doing matters to someone.
Ten Minutes
In the fall of 2024, YC announced something unexpected: they were adding a new batch, their first-ever fall cohort. Applications were open.
We hadn’t planned on this. We thought we had another few months to prepare. But here it was, and this time we did everything differently. We recorded a demo video. We made the application half as long but twice as clear – no fluff, no hedging, just the facts. We had paying customers now, real traction, a real story to tell.
We also reached out to YC alumni, probably a hundred of them, asking if they’d review our application before we submitted. Most didn’t reply, but about ten did. Their feedback was invaluable – small things mostly, phrasing that was unclear, claims that needed evidence, places where we’d buried the most important information.
We submitted. This time, we got an interview.
The YC interview is ten minutes. That’s it – ten minutes to convince a room of partners that you and your co-founder are worth betting on. Once ours was scheduled, we asked more YC alumni if they’d do mock interviews with us. Five to ten people agreed, and we’d get on calls where they’d pretend to be YC partners, firing questions at us like the real thing.
One of these stands out. The guy joined and immediately said, “All right, I don’t have a lot of time. What are you building?”
We gave our pitch: localization tools for developers, helps teams ship to new markets without thinking about translations.
He cut us off. “I’m going to be honest with you. I just interviewed another team with exactly the same idea. And I think this idea is bullshit.”
Then he started grilling us – why would anyone pay for this, isn’t this a solved problem, what makes you think you can compete with Google Translate. Hard and fast, for about ten minutes straight. I could feel my face getting hot. Veronica was visibly tense.
Then he stopped. His tone changed completely.
“Okay, that was staged,” he said. “I just wanted to help you prepare. You guys actually have a solid product. But you needed to feel what it’s like when someone comes at you hard.”
It was one of the most useful thirty minutes of the whole process. When you’ve already faced the hardest questions in practice, the real interview doesn’t feel as scary.
The day of the actual interview, we joined the video call a few minutes early with sweating palms. The interview started, they asked about our product and traction, why we were the right people to build this. We answered as concisely as we could – no rambling, no filler, just direct responses to direct questions.
Ten minutes later, it was over. We sat there looking at each other in that strange silence after something important ends. Neither of us could tell if it had gone well or badly. We felt like we hadn’t made any major mistakes, but was that a good sign? If we thought we did well, maybe we were missing something.
A few days later, YC reached out. They wanted to schedule another call – a deep dive into the technology we were building.
We got on the call and demoed everything. Walked them through how it worked, answered their technical questions, showed them what we’d built. And then, right there on that call, they told us we were in.
I don’t think I’ll ever forget that moment – the rush of relief, the disbelief, the sudden sense that everything was about to change.
And it did.
What I Know Now
If I could go back and tell myself something at the beginning of this journey – back when I was staring at an empty inbox in Barcelona, wondering if anyone would ever reply – it would be this:
Do the research first. Before you try to sell anything, talk to fifty people. Ask them about their problems and pay attention to the words they use. After enough conversations, you’ll start hearing the same phrases repeated, almost like a chorus. Those words aren’t random – they’re the key. Use them in your landing page, your emails, your pitch. That’s how you get strangers to feel like you understand them.
Always include a demo, even if your product looks boring, even if it’s just a terminal. The people who matter will understand, and the people who don’t weren’t going to fund you anyway.
Get help from people who’ve been through the process. Ask YC alumni to review your application, ask them to do mock interviews. You’d be surprised how few people actually do this. It’s an enormous advantage, and most of them are happy to help.
And finally, treat everything as an experiment. After each week, ask yourself honestly: am I getting closer to my goal? If the answer keeps being no, something needs to change – either the goal or the approach. You have to be willing to see this clearly, even when it hurts. Especially when it hurts.
I go hiking on weekends now, not every weekend but often enough. It’s easy to just keep working. There’s always another feature to ship, another email to send, another problem to solve. But when you’re deep in the work, you lose perspective. You stop asking whether the work is actually working.
The path to where you want to go isn’t always a straight line. Sometimes, to get to that place, you have to go somewhere else first.
That’s what this was – our path to YC. Veronica is convinced I should write more of these.
What would you like to read about next? Leave a reply.
love it! continue posting more newsletters, it is really good to read someone sharing honest things about the startup road