“How do I parse this string? I need to get the digital asset ID.”

Alongside excited chatter about how blockchain technology might one day disrupt a range of technology industries, this is the sort of nitty gritty technical discussion that permeated the first day of CoinDesk’s Consensus 2017 Building Blocks hackathon. Held over two days this weekend on the 40th floor of 30 Rockefeller Center, the event brought together a global selection of developers, designers and project managers.

While production software usually takes months or years to create, hackathon attendees have a total of about 30 hours to hack a project together, fueled by a dozen or so boxes of Todaro Bros’s coffee, bagels and pizza.

The hackathon featured a number of challenges, each sponsored by well-known startups and enterprises, including the Enterprise Ethereum Alliance, the Linux-led Hyperledger project, IBM and a half a dozen more. Automotive company Wanxiang wanted to see smart city applications, for instance, while insurance company Swiss Re asked developers to look into agricultural micro-insurance applications.

Although there were a range of challenges for developers to compete in, the hackathon didn’t have a strict theme. Rather, hackers have the freedom to build what want.

The result is was what looked like a technology buzzword paradise. Many teams ultimately chose to pair the technology with other industries that are drawing recent attention, such as Internet of Things and artificial intelligence. This meant there was a huge variation in projects. “They’re going to put rabbits on the blockchain,” one attendee joked.

Still, a couple of themes stood out. Despite the variety of blockchain choices, most of the projects were being built on ethereum.

Participant Yangbo Du explained that his team is working on a ethereum-based health care records system that could be paired with artificial intelligence to calculate risk. He expects that the blockchain prototype that they build at the hackathon will ultimately make it into his company’s product, a “personal risk advisor”, as he put it.

Autonomous cars on a blockchain

One team, with members largely hailing from Australia, was still in the early stages of planning their ethereum-based project while in conversation with CoinDesk.

They knew that they wanted to create an application that would help with safety in a future filled with autonomous cars, a technology some researchers believe will expand to households rapidly in the near future. But after generating a few ideas, they weren’t sure which one to run with.

“We’ve solved 15 different problems now and we’re not sure which one to choose,” participant Tim Bass joked.

In one idea, the team envisioned a future where roads feature a mix of types of cars, say 70% are autonomous, while the rest are still driven by humans. The problem in this scenario is that leaderless cars are typically better, more cautious drivers.

Their proposed solution is to penalize “bad” normal cars with “dickhead” tokens for driving poorly or taking advantage of the politeness of autonomous cars.

“If you continue to accrue these tokens, it would affect your driving history and your reputation,” Bass explained.

To accomplish this, they would gather data directly from the road (in the case of an accident for instance) that the insurance company could then use for the reputation system. Though, it’s worth noting that some have questioned whether this type of data collection can be accomplished in a “trustless” fashion.

Inevitable smart cities

Another ethereum project, tentatively called Smart City Protocol, could perhaps incorporate the autonomous car project somehow.

Developer Chase Thompson called the project an “open platform for masterplanning a smart city” in conversation with CoinDesk. In broad terms, you could think of it as an open-source smart contract for managing various aspects of a smart city, an idea that the team believes has been gaining momentum in the technology world. Developer Vishal Vinayak noted India launched a 20-city smart city program just last year.

Yet, the developers believe that other smart city projects haven’t been quite ambitious enough.

“Basically, smart contracts can handle everything, so we’re trying to build one that actually does,” said developer Morgan Sliman, adding that smart city applications range from energy management to tracking ownership of tokens.

“There are a lot of rabbit holes we can go down in terms of city management and how blockchains can integrate into that. But from a macro view, it’s a great way to keep track of communities and really every aspect of life,” Thompson added.

Developer Leon Do thinks that this sort of project is inevitable.

When asked whether the team would consider working on the project after the hackathon ends, he told CoinDesk:

“If it’s not us, somebody else will.”

Toward the real-world

With progress beyond the hackathon in mind, each company had a dedicated conference room where representatives gave product tutorials and where attendees could pop in to ask questions. For instance, IBM demoed Hyperledger Composer an open-source API for making blockchain applications faster to develop.

Still, this early in the game, imaginations might be in hyper-active mode and it’s impossible to say which blockchain applications will necessarily take off. (This shouldn’t be a surprise for such a new technology. Uncertainty about the future was exactly the case with the early Internet.)

Sponsors emphasized building applications that would be genuinely useful, perhaps especially since some hackathon attendees are only were poking their heads into the space for the first time.

In a presentation describing Deloitte’s end-to-end solution for bringing blockchain applications to production, consulting manager Savita Muley emphasized the importance of building applications that genuinely need blockchain technology.

She asked the audience of a couple dozen developers packed into a conference room:

“Is this really a blockchain solution? Or can you do it with other technologies?”

Deloitte’s reward will go to the application with “highest potential for commercialization.” The company plans to help the winning team bring their project to fruition with a three-hour consulting session in their Blockchain Lab in Wall Street.

Each group will present their prototypes to an audience and a panel of judges on Sunday afternoon.

Image via Alyssa Hertig for CoinDesk