Skip to main content

Berlin & Texas: Bitcoin Hackathon


This is a guest post by Brian Fabian Crain.

On the weekend of February 21-23, the Berlin & Texas Bitcoin Hackathon took place at the legendary hackerspace c-base in Berlin. The motto, Decentralize Everything!, was inspired by the recent projects aiming to bring the power of the blockchain to a broad range of applications. Many members of Berlin’s vibrant Bitcoin community were there, joined by visitors from other cities.

Inside the Spaceship

c-base turned out to be an awesome location: It was founded in 1995 as one of the world’s first hackerspaces and played an influential role in helping hackerspaces proliferate. It is also known for its close affiliation with the Chaos Computer Club, Europe’s largest association of hackers, and more recently the German Pirate Party was founded there. As impressive as its history is its interiors: It felt as if we had stumbled into the large relaxation area of a gigantic spaceship drifting off into space.

The event started off on Friday evening with a welcome by JF Gallas, the organizer of the event. Then Jörg Platzer gave one of his signature motivational speeches. He is also the owner of Room 77, the world’s first brick-and-mortar establishment to accept bitcoin, which provided great food throughout the weekend. Thomas Hessler, co-founder and former CEO of Zanox, talked about his new project UFOStart, the world’s first global crowd network for lean startups, which was sponsoring the event.

From Berlin to Texas

The hackathon was organized in collaboration with the upcoming Texas Bitcoin Conference in Austin, Texas on March 5 & 6. The tantalizing prize for the top four hackathon competitors was a trip to the conference and a chance to compete in the Texas Bitcoin 2.0 Hackathon with UFOStart covering the flights and the Texas Bitcoin Conference covering local accommodation and conference tickets. Before people dove into their projects, Paul Snow of the Texas Bitcoin Conference sent a greeting message from Texas.

Voting Convolutions

On Sunday, core Developer Mike Hearn came too to meet people and help out with the projects. Then the time for selecting the winning project came. One of the teams, Jeffcoin, had been building a Bitcoin-based voting system that we had planned to use for selecting the winners. Unfortunately, something wasn’t working when it came to the voting and we had to look for alternative methods. (This was probably to the advantage of the other teams since Jeffcoin was admirably transparent about building a rigged system so only they could win.) Mike Hearn made the strange proposal of voting by a raise of hands, but the idea was dismissed by everyone for being ridiculously uncomplicated and not digital enough. Instead, we settled on voting by SMS and the service showed the tallies live on the big screen. It was a close race, but in the end Coinswap won, followed by Supporttr and Jeffcoin.

1st place: Coinswap

Coinswap was developed by Felix Weis of Bitalo, who programmed the backend, and Dennis Wilson, who created the UI. Coinswap uses multi-signature addresses to allow trading between coins of different cryptocurrencies. Here is how it works: Let’s assume Alice wants to trade 2,000 Dogecoin with Bob for 1 bitcoin. They both meet on Coinswap, enter the details of the trade and are then shown QR codes. Alice pays her 2,000 DOGE into the multi-signature address and if Bob does the same with the bitcoin, the trade completes. If, however, Bob doesn’t send the bitcoin, Coinswap uses its private key to sign a transaction that refunds Alice her 2,000 DOGE. Thus Coinswap can provide the same escrow functionality of an exchange like Cryptsy but does so in a decentralized, semi-trustless way using multi-signature addresses.

2nd place: Supporttr

The runner-up was an Android app called Supporttr created by Java developer Christian Rotzoll. Supporttr implements the idea of micro-donations pioneered by the Swedish app Flattr. Users can select a monthly donation level, for example 5 mBTC, and then add different projects and charities in the app. At the end of the month, the 5 mBTC are split and paid out to all the projects. Through giving projects between one and three stars, the app also allows adjustment of the share given to each project. While there were still many details to be worked out, such as generating a single transaction with multiple outputs instead of separate transactions for each donation, the concept of smooth, recurring donations is great.

3rd Place & Other Projects:

The third place went to the previously mentioned bitcoin-based voting system Jeffcoin by Callum MacDonald, Hubert Gertis, Meinhard Benn, and Benjamin Wilson. Some other great projects included Bookr, a cool 3D representation of Bitstamp’s orderbook, by Jan Jorissen. Heinrich Erfurt and Dennis Mellman spent the weekend exploring Ethereum. Dirk Jäckel and Gustav Simonsson built a Bitcoin SPV wallet that looked like a cat with Lego Mindstorms EV3. When one sent a transaction to the address of the cat, it waved its arm in return. Björn Günzel and Doris Schleibinger worked on a 3D-printed paper wallet egg that would have the private key inside the egg.

While they didn’t quite manage to finish it, they announced a spectacular launch before Easter. Uwe Kamper built a website called ‘Yeah, let’s do it’ to improve Bitcoin-based crowdfunding. Users are able to post a donation address and a progress bar is updated with the incoming transactions to show how much has been raised. Hubert Gertis also briefly introduced Qllect, his project to create colored coins backed by creative works. In the end the winning teams, Felix Weis and Dennis Wilson, Christian Rotzoll of Supportr and Callum MacDonald of Jeffcoin, all won trips to Texas and they’ll be joined by Thomas Hessler and JF Gallas. 

Brian Fabian Crain is founder of the Bitcoin Startups Berlin group, founder/co-host of the Epicenter Bitcoin Podcast and writes a weekly newsletter analyzing the latest news and developments in the Bitcoin world.