Our Y Combinator Journey

Reflections and learnings from our YC W25 batch experience — from getting in to what's next for Mosaic.

Adish Jain
8 minutes read

Our Y Combinator batch ended a little over 2 weeks ago.
I've been delayed in making a post for this because I had a lot to reflect on and write about. But I think at a more subconscious level, I probably just didn't want to face the reality that YC is over.

We are now out in the wild, armed with the final piece of advice our group partners left us with: "Just don't die". In order to not die, I created a collection of my learnings from our YC journey as the first post on Mosaic's new blog.

This might be particularly useful for those interested in applying to YC, those currently going through YC, or anyone building an early-stage startup.

How to Get In

The Right Co-Founder

This must precede everything else. This will probably be someone you've known for at least a year. The best way to find a co-founder is by surrounding your self with really smart people and making it a point to reach out to the ones that stick out (e.g. I found Kyle while working at Tesla).

The Right Idea

Usually the right idea is always present, just waiting to be discovered. Tinkering around, being creative, and doing passion projects is a great way to uncover the right idea. For example, the idea for Mosaic came from tinkering around with video editing and trying to make a YouTube video as a creative outlet.

While tinkering, start by finding small optimizations that you think should exist. Have high agency and don't let the current state of the world dictate your thinking.

Build, Don't Write

Even though YC's applications are reviewed on a Rolling Basis, I would argue you should spend almost all of the application cycle building. Spend at most 2 hours writing your application, preferably the day before or the day of the due date. This forces you to be concise and get your point across quickly.

YC is reviewing thousands of applications, so skip the jargon and word-smithing. Focus on content, be succinct, and don't flourish. If you can't do this, you probably haven't thought about your idea enough and likely need to.

The first and second times I applied to YC, I spent days on the application, trying to perfect every word. With Mosaic, I wrote our application in ~1.5 hours the day before it was due and we submitted an hour before the deadline. Despite the rolling basis, we still got contacted within 5 days and got in a week after.

Don't Give Up

I applied to YC 3 times, rejected twice. The first time I applied was back in Winter 2021 while working on Leaf. The second time was in Fall 2024 while working on StreamQuest.

Both of those rejections had to happen for me to get on the right path. Every failure is just a re-alignment. Applying is great because you have to think critically about what you're building and what utility it offers. Plus if you get to the interview stage, you even get personalized feedback on what to improve. Use that and apply again. Never give up.

Learnings

Law of Attractions

Before you can do it, you must believe you can do it. Creating a startup is like giving birth with your co-founder (seed funding, laborious work — the analogy works well). Conceiving the idea is one thing, but having it materialize into reality is another. It's a constant marathon and requires a lot of positivity and determination. As soon as your mindset changes to a default "yes, we can do it," you really start to manifest that outcome.

Do Things that Don't Scale

This is perhaps one of the most common YC sayings after "Make something people want". Doing things that don't scale captures the essence of early-stage building. Especially today, with new advancements in AI coming out every day, speed and scrappiness are key. If you're overthinking your solutions, you're probably already behind. Just start.

Agency Creates Access

During the course of YC, we had the opportunity to have one on ones with icons like Paul Graham and Vinod Khosla, and hear from many more like Aravind Srinivas (Perplexity), Brian Chesky (Airbnb), Tony Xu (Doordash), and Greg Brockman (OpenAI). These are people who I had read of — or read the work of, in PG's case — for years, and now suddenly we were in the same room and conversation as them. Have high agency, and you can have unlimited access.

Get Used to Discomfort

I remember the first day of the batch, we all had to do a quick 1-minute introduction in front of the rest of our batch mates and group partners. I was nervous. But even though it was uncomfortable, I still took that and every subsequent opportunity I got to go and present in front of people.

During the course of YC, I ended up demo'ing 7 different times, standing in front of hundreds of people and saying my spiel over and over again. I got better each time, and we even ended up being voted the best demo in our group. Pushing yourself to be uncomfortable is the only way to grow.

It's Your Company

Something you need to quickly unlearn is the external validation type of thinking that has likely gotten you through high school, college, and early career. You're no longer completing assignments — whether that's homework or JIRA tickets — for someone else's approval or evaluation. You need to instill into yourself that this is your company and you get to run it however you want. So stop seeking approval or validation from anyone (except your users).

You Get Out What You Put In

YC does a great job of surrounding you with all the people and resources you would ever need to succeed. But these resources sit dormant unless you seek them out. Think deeply about how you can leverage this community of people and resources, and then proactively reach out. People are always willing to help, you need only ask.

Fundraising is a Game of FOMO

Early-stage fundraising is a game of strategy and perception. At this stage, investors are really looking for two things: (1) ideas with high potential and (2) founders who will work hard to unlock that potential. Of course having strong traction helps with fundraising, but even without it you can be successful. You just need to be able to confidently sell your vision and why the expected value is high.

Just by virtue of being in YC, you already have a strong advantage going into fundraising because of the dynamic that Demo Day creates, with many investors seeking out a handful of companies in a limited amount of time. Another practical way I created early FOMO is by friending a lot of investors on LinkedIn halfway through the batch and making daily posts highlighting what we were building. I called this "Feature February," and it not only kept me accountable but also made visible all the work we were doing. Building in public like this got us our first few checks without even taking any meetings and gave us strong initial momentum going into the fundraise.

Don't Get Distracted

At an early stage, you cannot afford distractions. Yet, distractions lie around every corner, often disguised as "productive endeavors". For instance, scrolling on X to learn about the latest AI can seem like a productive use of time. And then there are more insidious things, like administrative work or low-priority features. These resemble real work but are not as meaningful and present a large opportunity cost. Even fundraising, to some extent, is a distraction. Do not lose focus on what matters. At any given moment, know what matters and solely focus on it.

What's Next for Us

During the past few months of YC, there have been a lot of technical hurdles to jump over. We pushed through by navigating the idea maze quickly and grounding our decisions by constantly talking to users. Mosaic today looks a lot different than it looked 8 weeks ago, and we're just getting started.

Since YC ended, we have raised our seed round, secured an office space, and are adding brilliant engineers to our team. We've been shipping at high velocity and are pushing the boundaries of what multimodal AI and agentic video systems are capable of.

If you'd like to join us on the frontier, we're hiring! To apply, please email your resume and a short note on a project you're proud of to adish@usemosaic.ai.