Stellar Build Challenge #6 – the Results

Confusion. Disorder. Darkness. Without form. Without meaning. For unbroken millennia, seemingly forever, all creation is but a roiling emptiness—all existence, void—as the sublime mystery of the unknown and a nameless malevolence combine in absolute nullity. Oblivion holds silent, cruel dominion, and the universe writhes, pathetic in its vacant struggle; timeless, deathless, soulless, loathsome. Then, suddenly, from chaos, order. Behold! Obey!

Yes, the 6th Stellar Build Challenge is officially over. Below are your winners. This is a real photo of the judging process.

Before we get to the best of the many excellent projects we had the privilege to review, we want to point out that we received more submissions for this SBC than in all previous challenges combined.

Stellar Build Challenge Submission Volume

This is Stellar in microcosm. There’s an order of magnitude more interest in the Network now; and the combined talent applied to Stellar is much greater than it’s ever been. While these are welcome problems to have, we’re the first to admit that the Stellar Build Challenge has struggled to keep up.

To reflect the high quality of many of our entries, and as a show of our good faith and of our renewed commitment to the SBC, we’ve decided to award five times the prize pool we’d originally planned. So we will distribute roughly 2.7 million XLM to the winners, not the 550 thousand we previously announced.

We know we need to do a better job rewarding and encouraging the absolute best projects on our platform. The announcement for SBC #7 will contain clear details on how we plan to improve. But we’re prepared to make these promises today. We’re committed to:

– more transparency in how we make choices
– better communication throughout each Challenge cycle
– more emphasis on projects that further Stellar’s long-term success

Of the 324 submissions to SBC #6, 113 will get some award from us. Our community team of Ali Finkelstein, Rob Durst, and Zac Freundt handled the initial review rounds, and Jed McCaleb made the final prize distinctions.

The overall winners below will receive awards of 200,000 XLM each (with the two teams who reworked the Python SDK splitting their award) and the other finalists will receive 80,000 XLM. Congratulations to these projects and to the many other worthy submissions who received smaller awards. Details on SBC #7 will be released shortly.

The Overall Winners

We received SDKs in many languages—from Scala to Elixir to Rust. This iOS SDK was the best executed, most active, and best documented, and of course providing a client library for the Horizon API for iOS developers will further many other projects on Stellar. This team of four contributors is actively evolving their work—the latest commit happened just hours ago. SDF is especially interested in rewarding follow-through on an initial idea. This SDK is available on cocoapods and has over 100 downloads so far; it’s already being used in at least one notable project, the BlockEq wallet.

One of the goals of SBC is to improve worthwhile existing projects. Many of the most popular and widely used Stellar services, such as StellarTerm and Stellar Explorer, were submitted this round and will receive awards for their ongoing work. But the transformative relaunch of LupoEx as, completed in just a few months, deserves the highest level prize this Build Challenge. Stellarport now ranks as one of the top community-developed exchanges.

Documentation & Refactor of Stellar’s Python SDK

For this we named two co-winners, and here are their Galactic Talk announcements:
overcat and theaeolianmachine.

Together these projects constitute an incredible refactor and improvement of the Python library for communicating with a Stellar Horizon server; the documentation especially was vastly improved—here’s a live demo. We hope these changes will allow contributors to continue to improve the library.

The Other Finalists

We saw many notable security-focused submissions, including Stellar Authenticator, StellarGuard, and the ongoing development of the Ledger Nano S/Blue Support for Stellar. But the most promising security improvement to Stellar came from LumenBox, who developed an important improvement to the current Federation service. They describe the problem and their fix well, in their Galactic Talk announcement and in the issue they submitted to Stellar’s github:

“The Stellar Federation protocol is secured through HTTPS. All data connections from a wallet to the servers have to use HTTPS. While this is a good step towards security, there is one hole: what if the web server or the federation server gets compromised? DKIF (Domain Key Identified Federation) closes this hole and ensures a signed chain, from the DNS record down to the individual Federation record.”

Two questions people always have about a cryptocurrency’s network are: Does anyone run a node? and Is this thing really decentralized? Stellarbeat answers these questions by analyzing and visualizing the topology of our Network. is a node crawler and explorer; one that also shows node location and node software version. Not only is this tool immediately useful to SDF, but it could lead to deeper network analysis projects, such as a quantitative node ranking system like this one for Bitcoin. bills itself as “Your Unofficial Stellar Guide,” and the site has quickly become an indispensable source of Stellar tutorials, explanations, and news. Our community needs better resources, not just better tools, and is exactly the kind of explanatory and evangelizing work we hope to see more of.

Distributed Trustless Workers with Stellar, a Medium post, deserves special mention here, too, although we ultimately didn’t select it as a finalist. It’s a thought-provoking walkthrough of a novel Stellar Smart Contract application, complete with example code. The author received a substantial award for the piece.

Open Garden allows you to turn your phone into a wifi hotspot and get paid for your bandwidth; their payment tokens are issued on Stellar. The app is ambitious and well-designed, and their team has been very vocal about explaining to the wider world why Stellar is the right platform for them.

Alfred is a basic, yet effective, Stellar command-line interface. It uses NLP to create an intuitive user experience. It’s well-designed, and the developers folded in a multitude of features while maintaining a clear focus on friendliness and approachability.

In addition to the winners and finalists, there were over 100 other submissions that deserved at least some award from SDF; the complete list of those projects is here. Notifications and award amounts will be going out shortly.

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