How to Build a Viral Mini App on Celo I Sophia Dew

Hi everyone. I am Sophia. I lead developer relations at Cello. Who here is it their first ETH global? Anybody?

Wow. Oh my gosh, that's the majority of you guys. Congratulations. So proud of you all for making it here today and for learning about and attending the workshops. I'm going to be talking a bit about building mini apps on Cello.

specifically. These are one of the best ways, especially if you're a new builder, to get involved in a blockchain ecosystem, get users on your product, grow, and start a company. So, if those are some of your goals, I'm going to walk you through step by step what you can do, opportunities in the Cello ecosystem, and ideas for that you can actually make here at ETH Global. In case you're not familiar, this is our bounty. We're giving out $10,000 to the best mini app on Cello.

The first place will win $6,000. This is one of the largest first place prizes. Some of the requirements. This is really important. We want you to demo the mini app within the Farcaster wallet.

This allows us to actually test it. You can get real users, real testers, and I'll show you exactly how to do that as well. We want to make sure that you have onchain transactions on Cello. So that's either payments, a contract, something that's happening on the Cello blockchain is another requirement. And then something that's recommended.

We really recommend you focus on a realworld consumer use case for a wide general audience. Something that's fun, something that's creative, something that could go viral. And I'll tell you a little bit more about why. If you want to follow along with everything that I'll be talking about here, including the actual code, the specific uh things I'm pasting into my terminal, feel free to check out our GitHub. If in case you don't find this link and you want to find it out later, it's on our ETH global resources page.

It is also available on Cello.org discussions. You can click on tutorial, find this tutorial, and see exactly what I'll be going over in today's presentation. Cello is Ethereum L2 built for real world use cases and as of this Monday we are officially the top L2 in daily active addresses which is really cool. We're growing a ton and it's specifically driven by realworld use cases in mini apps within mini.

Minipay is a stablecoin wallet with a built-in miniapp discovery page integrated directly within the popular Opera mini browser. In case you're not familiar with Opera, Opera Mini is one of the top wallets in Africa. It actually offers a little bit of free data. So, there's tons of users on that wallet. And Mini Pay is natively integrated on that wallet and available as a standalone app on iOS and Android.

So, that wallet already has 11 million daily active users. And some of our top apps see over quarter million transactions a day. So there's a huge opportunity for you as a mini app builder to get a lot of audience and get a lot of distribution through these channels. But that's not the only place you can build mini apps within the Cello ecosystem. You can build mini apps on both Farcaster and Mini Pay.

What's great about Farcaster is Farcaster is a permissionless ecosystem, meaning you can deploy your app and get it listed in the mini app ecosystem on Farcaster today. And I'm in this tutorial, I'm going to walk through exactly what you need to do to get it listed. And then mini pay is more of a permissioned ecosystem. So come as you as we judge your projects, as you deploy on Cello, we'll we can we'll invite some of our favorite projects and actually introduce them to the mini pay team. A little bit about why you should build on Cello and what are the opportunities for you as a builder.

The number one for sure is real world reach. We're really proud that a lot of the users on Cello are people that are really excited and hungry about holding stable coins. That's why they're on Mini Pay. That's why they're interacting with their wallets. We pride ourselves and having real world use cases and things that people genuinely want to interact and do things on chain.

So when you build on Solo, you build for access to millions and millions of real world users. The other thing is we have cheap and fast transactions. Our transactions cost less than a cent. It's one of the cheapest layer 2s uh to build on top. They settle instantly pretty quickly and you can pay for gas in stable coins like CUSD and uh other other stable coins which you don't need a gas currency to actually pay for gas on Solo, making it a really nice seamless user experience for your end user.

Very easy upgrade path. The reason we tell a lot of builders, especially new builders that are coming into the ecosystem, to start off with Farcaster is because a Farcaster mini app can run in mini with minimal code changes. So you can have the same host, same instance of your mini app and it can serve two growing ecosystems, which is pretty cool. So we recommend a lot of people to just go in Minipe, get users, get attention, make sure it's a good polished app. And when that's working well, we'll invite you into the mini pay ecosystem to get more users and transactions there.

Another piece, we have a ton of builder support. Specifically, we have grant programs, builder programs where you can earn rewards, grants, funding at every stage. So, if you're a new builder all the way to ready a venturebacked company, we have grants and funding available for you. So, come find us in the booth if you're interested and um to learn more about that. For this bounty, we are specifically looking for creative use cases.

We want to see something that's fun, that's interesting, has the potential to go viral, has the when we tweet about it or if you do something about it, people go, "Oh my gosh, what a cool, unique, interesting app idea." We really want to emphasize a polished mobile user experience. Uh make sure that your app is mobile responsive. A quick tip, use inspect console. Click on the mobile toggle as you're building out your app to ensure that it looks nice on mobile.

Make sure that it's easy to use in a simple and clean UI. Um I and then the final one is we want to see a live demo on Farcaster. This just helps us ensure that other people can use your app. We can test your app and it does some transactions on the solo network. And for this is an important thing.

Make sure you're using the mini app lag me connector to autoconnect to the Farcaster wallet. When you open up that your app inside of Farcaster, it should not ask you to connect your wallet. It should be automatically connected to your wallet. That improves the user experience a ton. Some examples that have done really well, we had a Quest platform that has around 15,000 weekly transactions already and we just launched it a few weeks ago.

Zodiac cards. This one is built with self, so you can uh prove when your birthday is and based off of your birthday, you get a custom zodiac specific for you. So you don't even have to tell the app when your birthday is. You just prove it using self verifications. We have uh a kids wallet where you can earn rewards for doing tasks that kids would do.

We have cello polls, a bunch of great apps on mini. This is where most of our transactions and most of our apps also come from. We have we see a lot of use cases for stable coins because this is just a stable coin wallet. Things like games, things like local on and off ramps, paying local bills, buying gift cards, um all of these different things do really well on Mini Pay. Interesting use cases for stables or even ways for people to earn stables.

We're seeing daily claims, microtask rewards, things where people can earn rewards, earn stable coins do super super well as well on Many Pay. As you've seen, if you stopped by our booth, Cello is uh right next to Self. We're together. We're a happy family. Make sure to also interact with the self team.

Ask what they're building. If you're not familiar with self, they are uh they prove your humanity and based off your passport and biometrics ID. You can zk proof things like your nationality, your gender, your age, your birthday, and of that you're not on an OFAC list. lots of really cool identity verification proofs that you can get with self and they also have their own separate bounty. So if you build with and uh the verifications are on Cello.

So it's a easy way to double stack bounties. You can win Cell's rewards and Cello's reward allin one which is a pretty cool way to earn some bounties and prizes. All right. Okay. Let's jump into building.

I know the internet's not working super well, so this is will be fun to see how it works. Again, you can follow along with all the prompts that we're using here on our GitHub. So, we'll be using um Cello Composer. Cello Composer is uh if anyone's built with um let's see, I actually started this earlier. So, you can let's see if I can uh Okay.

Okay, I started this earlier in case the internet wouldn't load. Um, but if you want to find it all, all of the actual prompts I'm using are right here. You can go ahead and create a mini app template. So, I you'll paste that in there. Um, and it'll actually create you this app for you.

And what it has is, yeah, it has a project description and you get to select different templates to use from. So, we have a basic template, a forecaster, mini app template, mini pay app, AI agent, and it automatically creates all of this for you. So, I'll show you what that looks like. You don't have to use Cello Composer for building your app, but it is a great way to get a quick scaffold of all of the architecture that you'll need. It creates it in a monor repo structure.

So, if you're writing your own contract, if you're writing your front end, it's all here already on your app for you. Okay, let's pretend it loaded because I don't know how the internet is. And in case it didn't load, here is one that did load. So once you have your app here, I'll show you a bit of what it actually looks like. You can run pamp dev and it will open up a little mini app for you automatically.

Okay, cool. This one I already added some code to. And then always do the inspect element and change it to mobile view to see what it'll look like. It's automatically connected to your Farcaster wallet, which is really nice. As you open it up, I added a bit of onchain interactions here to just do some send some USDT usd to any wallet, but you don't Yeah, I added an extra prompt in case just to test it all out.

And then let's go back to our app. In another tab, you'll want to run a local deployment so you can get a link. And I'll show you how you can actually test it out in the forecaster wallet.

Why do we need what? So, inside of Farcaster, which we'll be testing it right now, when you actually test out your app, you'll This is how you can publish it. It's super easy. With just a few clicks, you can paste in your app and see what it'll look like and that's your app. And as you can see, it already has all of these things created for you within the Farcaster um mini app cello composer template.

So you have all of these as you go and then all you'll do is you'll generate an account association and this will assign it to your account. So you'll click this. You'll go back to your app. You'll open up your forecaster enviables and you will paste in these variables for each one. So this is my header right here.

This is my payload right here. And this is my signature right here. Cool. And then let me delete these. And let's go back to the app.

And you can reverify it. And now I have an assoc account association that matches. So yeah, we'll do that right now. Um, and so here you can see I have my account associated. And then we'll go down here.

We'll want to update our actual local our domain. So instead of be the local host, we'll have it be that Enro that we have. Where is that? Where do I have it hosted? Yeah, this Enro link.

And you could actually do this on Versel instead. Doesn't have to be. I'm just doing a quick one here to to show. And let's refresh it. And this should show our It automatically comes with a logo and a splash screen image, but obviously change that for your app.

But now your whole app actually works inside a forecaster. You can add your mini app. You can send some CUSD. You can test it and it all already works within the wallet which is really nice. And so now you have an instant Farcaster mini app.

It's that easy to deploy. And if you don't want to use Cello Composer, you definitely don't have to. But one of the things that you will have to do is ensure that your app when you have your wallet connection right here, you want to ensure that it's wrapped with the Farcaster mini app injector. So connector. So here I have my create my config variable and I have it wrapped with this WagMe provider.

So it's connected. It's connected there. And you can find that all of that information on uh the Farcaster docs as well on how to do that. So you you'll just want to ensure that you have this injector that when you open up any app within Farcaster, it's automatically connected to your wallet. In this tutorial, I'll also show you how you can test out your actual app inside of Mini Pay.

Uh, Mini Pay, it's mobile, so I can't show my screen right now with my mobile phone, but essentially what you'll do is you'll go to Mini Pay, you'll go to the developer settings, and then you can paste your app link right inside of that Mini Pay developer, and you can see exactly what your app would look like on Mini Pay, use it with the Mini Pay wallet, test it out with the Mini Pay wallet as well. And we have exact step-by-step details here for how you can test it out within Mini Pay. The other thing we have is we have a UI vibe coding prompt where you can use Cello's brand automatically and get our same fonts, get our colors, get a quick UI. I oneshotted it and that's how I got this UI. It's not perfect and beautiful, but it gives you something that at least doesn't look fully vibe coded that you can then polish.

So, this is just a one shot. This is not your end all beall. make it look a little prettier. But what we're for sure looking for is a polished enough UI. Uh oftent times if you're vibe coding your front end either with lovable or cursor, us as judges see a lot of the same looking front ends.

A really quick way to make sure that your project stands out and that judges remember you is to have a polished looking UI. We want to make that as simple as possible for you and that's what we have with this prompt. You can just paste that prompt in and that will give you enough to get started and then tweak it and polish it a little bit as well. So, and it looks like you're part of the Cello ecosystem with this nice branding which can be a uh a nice thing to do. Obviously, not a requirement though as well.

Those are the main steps for actually building and creating. But what I wanted to talk about as well is what's next for you after ETH global. Where do you go from here? How do you continue building on Cello, staying in the ecosystem and earn and start companies, start projects in the Cello ecosystem and grow? I wanted to share we have over $2 million right now in grant programs for builders.

You can find about out about all of these programs on cellog.eco/programs. and I wanted to share a few with you today that I would recommend a good path for you to get involved in right after ETH global. What are the next steps? We recommend after ETH global to sign up for proof of ship.

This is a monthly program where you can get you can create a project profile, get monthly rewards based off of you continuing to build, creating, continuing to create. So, that's a great way to get involved in the ecosystem. For some of the top mini apps, as you're live on Farcaster, we want to feature you in a miniapp Monday campaign. When you're live on the campaign, we will amplify from all of our socials and our Twitter. We will sponsor user incentive rewards.

We'll add you to one of our quest platforms to get even more people to test out your app. And we sponsor an airdrop to people who are using your app. and we promote the airdrop throughout the season to get even more users on your app. These are a great way to grow up your transactions. So, if you're looking for an investment deal later on, you're looking to grow, you can show this strong traction on your app.

We have presented growth grants. These are milestone based grants for mini apps. you if you have a good miniapp use case that we think would be great for the Cello ecosystem, you can get another $1,000 just for a live deployment in Cello, up to $5,000 for user incentives on your app, and up to $50,000 if Mini Pay thinks it's a good fit and you're scaling and growing and you're proving significant transaction volume and use case there. We have a cello builder fund. These are strategic investments dedicated just towards mini apps.

And next season, we're going to help builders launch mini app tokens. So tokens for their apps, for their communities that we'll support you with as well. So there are a lot of opportunities for you to grow in the Cello ecosystem and a lot of opportunities, especially after ETH Global. That's really what we want to emphasize. ETH Global here's for you to create, to experiment, to learn.

After ETH Global is where we get serious, we grow, and we scale. That's all for today. If you want to message me, my whole team, we will be at the Cello booth today, tomorrow, and on Sunday. But you can also DM me directly on Telegram at Sedophi on Twitter at Sedopi_. And I am also on Farcaster at Sophia.

If you're building any mini app, text me, message me on Farcaster. We have a group chat for builders uh who are building mini apps on Farcaster. I'll add you to that group chat. Send me a message, ask me to add you that group chat, and I can add you to that. They are great people to test out your apps, can give you lots of amazing feedback as well.

Awesome. That's all for today's workshop. What I have planned would love to open up the floor for some questions. We're out of time. We don't have time.

Never mind. We don't have questions. Time for questions. But if you do have questions, I'll be at the booth for the rest of the day. come by the booth and I can help answer any questions, validate any project ideas as well.