A Closer Look at the Winners of the 4th Stellar Build Challenge

Since launching last year, the quarterly Stellar Build Challenge has galvanized scores of developers from every corner of the globe to build their own applications atop The Stellar Network. Entrants into the Stellar Build Challenge are guided by the Stellar.org team and community in the various community forums and Stellar Public Slack to bring their ambitious and creative projects to fruition, and the results over the past year have shown the real depth of talent in the Stellar development community.

With the 4th Stellar Build Challenge concluding in July, a total of over 149 million Stellar Lumens have been awarded so far to projects ranging from contract wallets to exchanges and trading clients, payment solutions, and ICO launches. As an open-source blockchain network built specifically for the frictionless transfer of funds around the world, a key factor in Stellar’s growth is empowering developers from all over the spectrum to utilize Stellar in building financial technology solutions with real world usability.

Here’s a closer look at just a few of the winners of the 4th Stellar Build Challenge.


Popcoin is a simple, streamlined metered billing app that allows employers and employees to execute payment contracts based on deliverables, time committed, and other forms of metered arrangements. Aimed at developers in this early stage, Popcoin is instantly applicable to an array of industries, and its lightweight design, low fees, and eye-catching aesthetic render it an excellent candidate for user adoption.

Popcoin is developed by Tyler van der Hoeven, Creative Director of Tiny Anvil and a Front-End Developer at Baremetrics, based in Kentucky.

How did the parameters of the Build Challenge affect the way you approached Popcoin?
The nature of the Build Challenge really facilitated keeping things simple, while ensuring the product was also still useful and usable. I find that the more time you spend thinking through a project before you ever get to a computer, the better the final project will be.

How do you envision the Popcoin project developing?
Once it’s possible to move money into and out of more bank and credit accounts through the Stellar network, Popcoin will be the first and really only in class for the service that it offers. Stellar is the future, which at times can make the present more painful and slow to get going, but with patience, apps built on top of cryptocurrency are setting themselves up for seriously big wins.


ToNaira is a remittance app built specifically to address the Nigerian market. Africa is the most under-served and over-charged remittance market in the world, and by using the Stellar Network to transmit value via the Stellar-based NGN—Nigerian Naira Asset— ToNaira can transfer funds at a fraction of a fraction of current rates, which can be withdrawn into Nigerian fiat Naira quickly and at minimal cost.

ToNaira was built by Gbolahan Onadeko, a Business Administration grad from Lagos and a self-taught developer….

What makes Nigeria in particular a good market for remittances on the blockchain?
Nigeria accounted for $35 billion USD sent to Africa in 2016, and it was all processed through non-blockchain remittance companies that charged up to 20% as a sending fee. It is a good market for a blockchain based remittance company like Tonaira, because we are able to cut costs to as low as 1%, and offer this service for far cheaper than the already existing services in place.

How did you benefit from building ToNaira with input from the Stellar community?
The Stellar community on Slack is like family, and people always take time out to help work through with whatever questions you may have. I was able to understand blockchain better, processes and how to kick off Tonaira in a short period of time, much thanks to Jed and the Stellar Community.


PapayaBot is a multi-currency wallet that enables users to trade digital currencies peer-to-peer within the resoundingly popular messaging app Telegram. By chatting with the PapayaBot within the familiar Telegram interface, users can store and trade tokens built on the Stellar Network, in addition to Bitcoin, and then promptly return to their running conversations, without ever having to leave the Telegram app.

PapayaBot was created by Sergey Yusupov, a cryptocurrency software engineer based in Sydney, Australia

What is your goal with PapayaBot?
Papaya is something I’ve wanted to build for years, but never had the time. My aim is to make a wallet with multi-currency support that’s easy to use, fast, and secure. The goal is to have peer-to-peer marketplace, similar to Localbitcoins, but for any currency.

Why did you choose Telegram and Stellar to work on in particular?
I chose Telegram because it’s my favorite messenger. It’s the most secure—maybe after Signal messenger—and has way more exciting features, and is more user-friendly than any other app. And because it has native clients, users don’t have to install yet another app. Using Stellar is the number one choice if you want to do cross-currency trading. It’s also cheap, open, and easy to use.


Lightweight and versatile, the multi-platform blackwallet is built specifically for Stellar Lumens, and can run on smartphones, tablets, computers, pretty much anything that can browse the web and run javascript. Further, there’s no installation or registration required, all you need is a secret key to log into your wallet, and you can hold multiple wallets at once.

Blackwallet is built by Alexi, an IT student based in France who has been holding Stellar lumens since 2014.

What would you say is the most remarkable difference between blackwallet and other wallets?
This is what I had in mind when developing blackwallet: making it as simple as possible while being powerful and having rich features. Although I’m pretty happy with what blackwallet is at the moment, I am by no means done with it—many updates are still to come!

How was it getting feedback from the Stellar community when developing blackwallet?
It’s motivating. I’ve spent a lot of time developing blackwallet, and it’s always good to know that you are not simply spending hours doing that for nothing. It’s good to know that what you are building is actually used and appreciated (or not!) by the community. It’s also a good way to know what features you should focus on, what features should be added or modified, or what aspects may be buggy, tricky, misleading, or missing.


An ambitious project based in Kampala, Uganda, eSACCO is a social banking app that looks to provide the advantage of traditional banking services along with an added layer of digital currency functionality to intended users, many of whom are unbanked. In addition to offering savings, loans, and currency storage, users can earn by holding ESDT—The eSACCO Dividend Token. The ESDT ICO launch is ongoing until the latter half of September, and is just one of a number of promising token generation events built on The Stellar Network.

eSACCO is built in partnership with Clic.World, and is headquartered in Kampala, Uganda…

What was one advantage of launching eSACCO on the Stellar Network?
It was just so easy! Not having to worry much about the technical aspect of issuing the actual token, we could spend all our time and effort on the business side. Issuing the token was actually a direct result of the encouragement of the Stellar community, and Tunde in particular, who recognized the potential of ICOs to raise investment for the large existing savings and credit cooperative sector. While it was something new for us, it was the help and support of the community that convinced us to take the first step, and they assisted us with practical advice the whole way.

How are attitudes towards digital banking and blockchain technology developing in Uganda and the surrounding region?
Digital banking is the norm, with mobile money leading the way. Entries into the market like eSACCO, based on the Clic.World platform, are taking this to the next level with more services and products and driving the cost of transaction down. We see a large growth potential for blockchain based solutions over the next two years. There’s a huge appetite in general for anything new in the digital space here, with people prepared to try new innovations.

But the single biggest obstacle to a wider participation in crypto-asset that we face is our exclusion—as in most parts of Africa—from easy access to digital currency exchanges. At the moment, it is extremely difficult to get any kind of account opened at one of the major exchanges, and coupled with very limited availability of bank cards, makes participation in the emerging digital asset market something available to less than 0.01 of the population. So, yes, the appetite is certainly there, but access is very limited. We hope that Stellar will provide the opportunity for Ugandans to bridge this gap.

Find out how to get involved in the next Stellar Build Challenge, and stop by the Stellar Slack and the Community Forums to learn more about The Stellar Network.

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