Joe Petrich

Product solutions engineer @google-pay, Pitt CS grad, ham radio enthusiast, linguist

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The opinions stated here are my own, not those of my company.


Building Openhouse at the ETHGlobal HackMoney Hackathon

Published Jul 24, 2021

I’ve been interested in cryptocurrency, and especially Ethereum, for a few years, but never made the time to learn the technical side of it. I understood the basics of smart contracts, and the differences between Bitcoin and Ethereum, but, having followed the Ethereum ecosystem more closely for a few months, I decided I wanted to dive deeper into Ethereum, smart contracts, and web3 tools. I got permission from my company to participate, and signed up for the 2021 ETHGlobal HackMoney hackathon!

Getting started

ETHGlobal has an interesting sign-up system for their hackathons. In addition to an application (which seemed designed mainly to weed out bots and low-effort submissions), upon approval, participants must “stake” a small amount of ETH. This is done by logging into their site with an Ethereum wallet, and clicking on a button which prompts you to authorize the transfer of the ETH to the hackathon’s address. Participants receive their stake back at the end of the hackathon, as long as they complete required checkins and submit anything at the end of it. This really appealed to me, despite losing the gas cost, because it provided an incentive to complete the hackathon and not bail out without finishing something.

Finding a team

After signing up, I was able to join the ETHGlobal Discord server, and verify that I was a participant in the hackathon, again, using my Ethereum wallet. There were channels for making introductions and finding teams. I joined without knowing anyone else participating, and had planned on hacking solo unless I could find a project that was really compelling and willing to take on someone like me, with no Ethereum programming experience. I was surprised to find many such teams! Some teams I talked to included the teams behind Pods and PWN.

In my introduction, I mentioned my interest in building identity and authorization solutions based on Ethereum wallets. While I found these, and other DeFi projects, interesting, I am personally more interested in the future of web3, where users control their digital identities completely by identifying themselves with their private keys, and therefore have the ability to reset their identities at any point by generating new keys. Projects like ENS that make it easy for users to associate human-readable information with their private key really appeal to me, and I think the future of the web will rely on systems like that. I hope that I will one day be able to log in to pay my taxes or manage my healthcare with my keys secured by my hardware wallet, that I will be able to engage with friends and strangers on social media by logging in with a browser extension wallet, and that I might have yet another wallet with a small amount of ETH, Bitcoin, or stablecoins that replaces my leather wallet full of cards and cash today.

My introduction resonated with another participant, Chris, who had experience with web3 livestreaming technology, and was interested in building web3 solutions to help facilitate online communities in a decentralized manner. Through talking with him, we refined our ideas, and agreed to work together after recruiting Drew, and, eventually, Prabhu, two more software engineers. By the start of the hackathon we were ready to start building what we called Openhouse, a video meeting platform with web3 login and access controlled through ERC721 tokens.

Hacking away

This was my first experience participating in a virtual hackathon, and I wasn’t sure what to expect. I had participated in in-person hackathons before: 48 hour endeavors with little time to sleep, let alone think! I found the pace of a 3 week hackathon much more enjoyable, and I appreciated the ability to work with teammates across many timezones asynchronously. The pace gave me the opportunity to study Solidity, SvelteKit (the JavaScript framework we used), Jitsi (the open-source video conferencing software we used), and various other SDKs, understand them, and make conscious architecture decisions that led to a much more readable and improvable final product than we could have accomplished in a 48 hour sprint. I’m not sure yet whether we’ll keep working on Openhouse after the hackathon, but if we do, or anyone else wants to, our GitHub is in a good state to pick up and keep on hacking.

Final thoughts

Our submission for Openhouse is on the ETHGlobal showcase site. At least for now, you can also play with it at, where it’s live on Polygon. The code is on GitHub, and the smart contract address on Polygon is 0x151A051FE0a9414950Ef0B34030294cEaB6F043a.

I learned a ton about web3 and Ethereum smart contracts in just thre weeks by participating in this hackathon, and I’d encourage any web2 developers to give a future ETHGlobla hackathon a try. By the end of the Hackathon, I had a better understanding of multisig wallets, Solidity, ERC721 tokens, web3.js, and ENS. The haze of terminology and only superficially understood technology that clouded my understanding of web3 before has now been lifted, and I feel confident to continue developing on top of Ethereum in the future.