I Built a $20K/Month App in 83 Days

0:00This started as a fun side project, but we turned it into a real business. Meet Brian. He and his girlfriend built a really simple mobile app, and in less than 3 months, they grew it to over $20,000 [music] a month. We set a number and didn't start building until we hit it. You might think he validated the idea like everyone else, but no. He did something I've never seen before, and it's called [music] the commitment metric. We made sure that people committed to this product before writing a single line of code. So, I brought Brian onto the channel to break it all down for me. In

0:32this episode, we'll dive into the amazingly simple app that makes over $20,000 a month, why you should resist the temptation to build anything until you hit this one number, and the new framework to validate business ideas in an AI world. This one is a great story, so let's dive [music] in. I'm Pat Walls,

0:52and this is Starter Story. All right. Welcome Brian to the channel. Tell me about who you are, what app you built, and what's your story. Hey Pat, nice to meet you. My name is Brian Shin, and we built a disposable camera app called Once. We launched back in December 2025, [music] and fortunately, we were able to hit 20K in monthly revenue within 83 days of launch. So, today, I really want to share exactly how we pre-validated Once before [music] writing a single line of code, and also some of the growth playbooks that we had to grow Once from zero all the way to

1:23$20,000 in monthly revenue. Okay, cool. I mean, awesome to have you here. Would you be able to just explain what your app does, who uses it, and pull up some of your revenue dashboards to show that this is legit to the audience? Yeah, for sure. So, Once is basically a disposable camera for events, especially for weddings, birthday parties, and these days even for some corporate events. So, anything where a group of people can come together, have fun, and capture all the candid moments, Once can play a role there. And our pricing is based on the number of guests that you want to invite into your event. So, if it's like a

1:55small birthday party with just 10 people, it's going to be just $2. But, if it's like a bigger wedding for instance, if it's like 150 people, it'll be $50. So, that's the more usage, the more guests, the more higher tier that you would need to purchase in order to use [music] Once. So, it's been around 3 months since launching, and our weekly active users is around 10,000 to 12,000 users at the moment. And in terms of revenue, this month we're totaling

2:19around $22,000. And this is our internal dashboard calendar where you can see all of our active users who have scheduled an event through Once. And as you can see, in February, there are around more than 300 events. And for March, we got around 700 events coming up real soon. Here's what I love about Brian's story. It's a great example of someone who focused on growth and then hit $20,000 a month in less

2:42than 90 days. And this got me thinking. We talked to dozens of mobile app founders every week right here in this channel, and I always ask them the same question. How did you actually grow your app? Well, since we talked to so many people, we decided to turn all of their answers into a free guide that you can download right now. It's called the mobile app growth cheat sheet, and inside you will find the seven different marketing tactics that are working for real founders right now making money with mobile apps. If you're ready to focus on growth and actually grow your app, just head to the first link in the

3:14description to download the entire guide for free. I promise it won't disappoint. All right, let's get back to the episode. Okay, cool. I mean, this looks like a really cool app. I can see why it's popular and why it's growing. I want to understand a little bit about your background. How did you get to this point where you're building this cool consumer app that over 300 people are

3:33about to use this month at events? What's your background? So, before founding Once, I co-founded a venture-backed B2B startup. It's completely different from Once. It was more of a heavy sales-driven 50-person company. So, building this venture-backed startup really showed me what a real business is and everything related to building a fast-growth company. And while I was at the company, I found the whole bootstrap scene, which I didn't know existed before. I met all these really cool indie hackers and bootstrap founders who are validating in a very small way, so that it's rather a safer, smaller bet, as opposed to betting your whole life on something that's bigger. And I don't think there's

4:08right or wrong here, but I really wanted to try this new path of building a bootstrap company. And that's why this time I really wanted full control over the product that we built. Hence me and my co-founder, my girlfriend, we decided to go fully bootstrap this time. Okay, cool. Let's switch topics a little bit and talk about the idea. So, how do you actually find the idea for this app that

4:27eventually makes over $20,000 a month? The whole story comes from me and my co-founder, who is my girlfriend. Just last year we traveled to almost seven, eight different countries, and every single city we go to, we bring around a disposable camera. If you try using a disposable camera, it's [music] such a simple product, but it's so magical in a way that it has so many limitations. You can't see the photo right away. You have a limited amount of shots, but I think those limitations, it actually makes the whole experience much real. So, really the whole idea behind Once was, why don't we try to build [music] a digital

5:00experience that almost replicates that traditional disposable camera, was the whole idea behind it. That's awesome. Let's talk about how you built this app. How long did it take to build this app, and what was that journey like? So, the first version took around a week or two. It was a web app that kind of just had the core features of what a mobile app intended to have. We had a Halloween party hosted by my friend coming up, so we built out this web version. We printed out some invitation codes, so that everyone in the party can join in, take photos. And honestly, it broke many times during the event, but we were able

5:32to validate the core idea that people love taking photos in that event into [music] a singular album of each other through an experience that mocks the whole disposable camera experience. So, it didn't need to be perfect, but it was perfect enough to validate what we wanted to check. Another question is, AI. I mean, you just built this like 3 months ago. Did you just build it with AI tools or what tools did you use? Uh it might be a hot take, but after we validated with the web app, we threw out the first version. And that's because I honestly believe that consumer app is basically a craft. And I use a lot of AI

6:05for dev, for finance, for everything, but for design, we never use AI. And that's because we really believe that design requires taste. And we think that the more opinionated, the better design that could possibly come out. But aside from that, I I basically live on Cloud Code. Yeah, I mean, I 100% agree with that. Design is one of those things that AI is not that good at yet. And when you have a B2C app like this, a consumer-facing [music] app, you want it to feel This isn't just for utility, this is for fun, creativeness. So, I agree on that. Let's talk about the tech stack. What did you

6:36actually use to build this? All of our designs live inside Figma. And for the [music] dev part, feel like I I'm stuck with Cloud Code. And I started off with just a single terminal instance of Cloud Code Max, but I was recommended this tool called Conductor, where you can run several instances of Cloud Code to work on different [music] work trees at the same time. And we use Superbase for our database and back end. The web app used to live on Vercel, but we still have it

7:01running web aspects of the product. Okay, cool. We talked a lot about building, but I think maybe the more important thing here is validating. So, tell me about how you validated once. I did two things to validate our product and to get the first customers. Most obviously thing that you can do is just go through your personal network. And what I do is I open up three different tabs. I have my X open, I have my LinkedIn open, and I have my Instagram or Facebook open up. I have my friends list. I just go through every single one

7:28of them and see who might be a good fit. So, literally, I circled everyone who had a potential event coming up, and it was four friends who said, "Okay, I would love to try it." It was a Halloween party, birthday party, one wedding, and one networking event. So, this is the second part. Now, you have to go outside of your inner circle and really try to reach out to everyone who could be your potential customer. So, what I did was since once could be used at parties, at events, at weddings, I searched on Instagram #wedding, #birthdayparty, and cross-platform we

7:58had around 250 to 300 people listed out. I wrote down a very simple cold message type of two to three sentences max that could grab their attention and try to pitch your idea so that they can try it out. Amongst the 250 people we got around 15 people who reached back and we got around 12 events fixed for that single month and that's when me and my co-founder decided, "Okay, this does have market potential. Let's try to go all in and try to build out something

8:22that's really cool." This is awesome. I've never heard of validation in this sort of framing before. So, let's talk about this a little bit more. You got your app from zero to 20K in basically 83 days. If you had to start over today, what would be your playbook? Step one would be to define your commitment metric. And commitment here means two different [music] things. Commitment for yourself and commitment for your potential users as well. For yourself, set a specific date and specific number of customers or clients or other metrics that you would like to see within that date range. And at least you know that this is a finite number of days that you

8:57are dedicating and investing to validate your business in a certain amount of time. And the commitment metric of the client to signal validation doesn't always need to be payment. So, for us it was event hosts using our product within those events. So, based on your vertical, based on your product, there must be some type of metric that truly represents usage. And yeah, once you have that commitment metric out, I guess step two would be to exhaust your personal network. Just open up all of your social media profiles and try to see who you can reach out to, whoever

9:28relevant to your ideal customer profile. And one of the most important things when talking to your friends and family is a very famous concept, but it's called the mom [music] test, which is if you try to validate a product with your mother, she would probably be very excited about whatever you build. And that is honestly not the best way to validate your product. So, just be honest with yourself so that you are sure that you're validating the product as opposed to trying to find encouragement for your product. So, that's step two. Well, step three is the real part, which is to build a quick mock-up. Don't spend more than two to

9:58three days with this. Just [music] go on Figma or just use many of these AI tools that's out there. No matter how crappy it is, just try to find that really simple [music] product that you can present to your users. And once you have that, step four is to go wherever your users are living in and are active in.

10:14Just start from zero. Go to Reddit. Learn the ins and outs of Reddit if Reddit [music] is the place to be, or if that's TikTok, or if that's YouTube. Because this channel will not only be used for validation, but if the validation works, it'll be your main marketing channel in the future also. So, do so much cold mailing, cold messaging. Honestly, what I tell other friends and founders is that if you haven't been banned in these platforms at least two times, you haven't tried enough. And step five is to set that number that gives you enough signal or confidence that this product has potential. [music] For us internally,

10:45the goal was simple. Before writing a single line of code, I needed 10 events with an actual date, with an actual commitment that they would like to try using our product. Having a commitment to actually use at an event where you have your friends, your family, your loved ones there, we thought that was already a big enough commitment that it was almost proxy to a payment. And so, this would be the exact playbook that I would be using if I had to start all over today. Well, I love this validation playbook. I think a lot of people watching this go rewind, start it over, watch it again. This sort of commitment

11:14metric, this restraint thing sounds scary. It sounds hard, but it will save you so much time not building the wrong thing. So, I love that. Let's switch topics a little bit. And I want to see your app. Can you give me a demo of your app that made over $20,000 last month? Our app is really simple. And what you can do is create your own film. You name your own film, let's say Brian's party. And you can choose the date it ends, choose when your photos reveal, like a disposable camera, your filters, some of the invitation card when you invite your guests. And you can also

11:48choose how many participants you want to invite and the shots per person. You wait out until your film is created. Once it is, you can start taking photos and yeah, like a disposable camera, this will all be saved up and based on your reveal settings, this might reveal later or might reveal now and you can check everyone's photos in this album where everyone's photos all gather up in one area. Cool. Okay, well, that's an awesome app. I love apps like this, super cool. Last question that we ask all founders who come on Starter Story, what would be your advice to young Brian or for anyone watching this who wants to

12:23come up with a cool app idea like you, make money, do indie hacking, what would be your advice? I think the most important would be to [music] stop overthinking and just launch. Because I used to be a person who overthinks a lot. How do I do marketing? How do I do sales? And all blah blah blah. But I realized that those are really not the most important things if

12:41you're trying to go zero to one. [music] Rather, just spend that time talking to more users and just building out the very first version in like a week [music] or two maximum and just launch. Because all of your assumptions and all of your guesswork may go to nothing once you launch and once users start using it. You might be solving a whole new different problem than what you were initially expecting. So, really stop overthinking and launch [music] as fast as possible. Thanks for coming on, Brian, and sharing. Super cool app. I think it's going to grow a lot. Thanks

13:11for coming on and sharing everything. All right, man. Thanks a lot. All right, Gus from Starter Story. What do you think of this business, this app, Once Film? First thought is really cool product. A lot of mobile app founders we talked to, I feel like we've seen it before to some degree. I haven't exactly seen an app quite like this. I know it probably does exist. But that's my first thought is like just a cool product and like a cool dude. A lot of people have weddings and want this sort of thing in this like social media organic world that we live

13:39in. I had a wedding, you had a wedding. I'm sure you get all these like professional photographs, but they're like super lame and you don't even post those to social media. You just post like the selfies you took or or whatever. So I actually think this is like from a growth perspective, this app is going to be huge. Maybe we can have him back on the channel when I think it's going to grow fast and hits, you know, a million dollars a year or wherever it gets and we can talk more about the growth of that. So let us know in the comments if you want to see us talk more about how

14:09he grew that. I think his validation strategy was really smart. What do you think about that? Yeah, that was it was really like compelling cuz, you know, I've tried to start like my apps and stuff like that and I totally fall into the trap of [music] like building it first. And with Claude Co and all these AI tools, it makes it so easy to do it and then avoid the hard part. [laughter] You know, when he was when he was talking about like go through your contacts and reach out to people, man, I could feel myself sort of like cringing up a little bit like I can't imagine

14:40like messaging a random person from 10 years ago when I went to college and being like, "Hey, I built this. Like, what do you think?" But I think that's definitely like a beginner's mindset. You're spot on with that. Before when it was hard to build stuff, you had to ask people and then decide you would build it. That would be like the natural way to do things cuz you just couldn't build it. Now I think that AI tools are such a crutch in that sense is that like, "Oh, I have a cool idea." Instead of talking

15:04to people, I'm just going to build it. Then you build it, it works and it's awesome. And then you don't know what to do next. You're scared, it doesn't exactly look as good as you wanted it to. So then it, you know, maybe demotivates you from doing this very, very important thing, which is sharing it with random people that you haven't talked to in 10 years. This is the scary stuff. So, hopefully a lot of people watching this realize that, "Oh, in a world where anyone can build anything in 1 hour, this is the secret sauce. Going out and setting your commitment metric of I need 10 people to say they're going to

15:37use this thing before I finish it." So, if you're thinking about doing the same, you may even build some stuff before or you're thinking about jumping into Cloud Code and starting to build an app, stop right there and instead go click the link in the description to learn about how to actually grow and validate a mobile app. We put together the top growth strategies for growing a mobile app, an iOS app, a B2C app. You can click that right down there in the

16:02description and get it 100% for free. All right, I hope you guys enjoyed this episode of Starter Story. We'll see you in the next one. Peace.