Three teams at the 2018 September ETH San Francisco Hackathon won the Chainlink hackathon prizes for their implementations of Chainlink on the Ethereum blockchain.

Hackathon entrants pit their technical skills against each other over a 36-hour weekend to build a working blockchain application. Chainlink awarded prizes to the teams with the most creative and compelling prototypes of Chainlink. As the applications of off-chain data to on-chain smart contracts are endless, we saw huge variety in projects ranging from political voting, to cryptocurrency finance, to contract uptime guarantees.

Taking the $1,000 third prize was B3PO, a project that merges robotics and blockchain technology. The team created a system that handwrites blockchain-validated information on an absentee voting ballot to be sent through the mail. It’s a provocative workaround for voting on the blockchain.

The idea was born when software engineer Moyukh Sen learned of a swing race in his hometown of Buffalo, New York a few weeks before the hackathon. He knew that college students away from their hometowns wanted to vote, but most don’t know the first step of the absentee ballot process. To solve this problem, Sen’s team bought a $200 robot from Amazon and got to work. He built a robot that would handwrite absentee ballots using smart contracts secured on the blockchain. By partnering with university clubs around the country — blockchain meetups, robotics groups, and political clubs — he hopes B3PO will make it simple for students to cast their absentee votes no matter where they are. The end of this video shows the finished robot in action:

“Getting that dynamic ballot data into the smart contract on-chain requires an oracle service, and Chainlink is a great fit for that,” said Sen. “Google aggregates a lot of voter data as a service, so we wrote an adapter between Chainlink and the Google voter API. It was very simple to do and has great democratic benefits.”

Second prize of $2,000 went to Link Set, a project aimed at crypto traders who want a more automated trading experience. As values shift across your portfolio of tokens, Link Set can rebalance your cryptocurrency portfolio, automatically executing trades based on real-world price changes. Additionally, traders can create a basket of cryptocurrencies that rebalances over time, similar to starting your own S&P 500.

“We’re familiar with standard exchange-traded funds that let you track an index. We were interested in doing that with crypto,” said Link Set team member Sharad Shekar. “Autonomous rebalancing could revolutionize the way cryptocurrency investment works.” Team member Edmund Miller adds, “The goal was to make a trustless system and that was easily managed by Chainlink.”

Taking first prize and $4,000, “solo hacker” Xuefeng Zhu won the Chainlink hackathon. His application, Micro Subscription, holds cloud providers accountable to their guarantees by monitoring server uptime data. Micro Subscription uses an on-chain oracle to establish a smart contract between the user and the provider. It pays out according to a company’s stated service level agreement (SLA) and ensures the customer doesn’t pay for any downtime.

“Paying for cloud service by flat rate requires more capital flow,” Zhu said. “My project lets the user pay for what they use, like by-the-minute phone service.”

These hackathon winners show a variety of applications demonstrating how bringing secure external data to a blockchain paradigm can impact our world today and in the future.