Community, Creativity, and o1js: A Recap of ZK Hack Istanbul

Last month, the o1Labs team gathered in Istanbul, a city steeped in history and vibrant culture. The days were filled with productive sessions of product planning and team building at our company offsite on Büyükada. The momentum continued in the meeting point of the world with a flurry of DevConnect’s Web3 and ZK events.


Last month, the o1Labs team gathered in Istanbul, a city steeped in history and vibrant culture. The days were filled with productive sessions of product planning and team building at our company offsite on Büyükada. The momentum continued in the meeting point of the world with a flurry of DevConnect’s Web3 and ZK events.

Amidst this flurry, one of the key events for our team, ZK Hack, took place. It brought together the best and brightest of the community to learn about the newest developments in zk and to kickstart their learning journey or business ideas. The o1Labs team showed up in full force, actively engaging with developers, sharing insights, and discussing various projects.

The event kicked off with informative workshops from sponsors, including us at o1Labs, where we covered a spectrum of o1js use cases, sparking a notable interest among participants due to the accessible nature and powerful functionality of o1js. We sponsored five bounties covering a range across gaming, voting, crypto primitives, data structures, and an ‘open sky’. The ZK Hack workshops are intended to provide developers with the context needed to choose a technology to work with and the right bounty to hunt! We especially enjoyed hearing directly from the other teams working on zk and seeing the progress we continue to collectively make in this nascent ecosystem.

Over the subsequent days, we split our time between engaging with participants, providing assistance in application design and debugging, and fostering connections. Office Hours on Saturday proved to be particularly fruitful, offering an interactive platform for the community to engage with our developer relations team. It was incredibly insightful to hear questions from developers working with o1js for the first time, and our team left with many valuable takeaways.

The best part about the event was meeting and engaging with developers, both experienced and novice to zk!

As the hackathon and weekend came to a close, prizes were awarded to commendable projects that showcased innovative applications and creative uses of zk technology. The diverse range of ideas presented, from enhanced voting mechanisms to gaming applications, highlighted the potential of the ecosystem. o1Labs awarded prizes to seven projects, two of which were also awarded the general ZK Hack prizes.

The Winners

Katz lets you vote for your favorite candidate with greater anonymity. By leveraging recursive proofs with o1js and using Mina to settle the election results on-chain, your vote is kept private from the rest of the public, while the overall election results can be known by anyone.
(Also won Top Projects Prize by ZK Hack Istanbul.)

o1js SHA
Uses o1js’s newly released bitwise operations gadgets to optimize the SHA256 circuit implementation by operating on the 32-bit words (32 field elements) as a single field element utilizing native binary gadgets.
(Also won the ‘Chewing Glass’ Prize by ZK Hack Istanbul, awarded to those providing technical contributions to zk.)

An election system that uses zero-knowledge proofs to protect ballot secrecy and mitigate the risk of vote manipulation with a lightweight solution that scales for large elections.

Groth Makers
Built upon the foreign field arithmetic implementation in Snarky library to attempt Groth16 verification in o1js. Partially completed with a bn254 implementation.

Lets people play poker trustlessly with each other without having to trust a central authority or each other. Poker based on cryptography. Trust the math!

Aargon is a 1998 puzzle game where the player completes objectives using lasers and mirrors in a 2D grid. zkAargon was built to prove a solution to a puzzle without revealing how.

Two and a half zk
pocket-kimchi provides mobile bindings for o1js to the underlying Kimchi Rust proof system for Swift. This allows for the execution of proofs and verifications natively on mobile devices.

Developer Engagement

Post-event, our community engagement continued as participants generously shared their experiences and provided valuable feedback to our product team. Developer insights are instrumental in shaping the future roadmap for o1js, and we’re committed to implementing improvements based on your feedback and suggestions. As we always say, DevX is at the heart of what we do!

The team thoroughly enjoyed the experience at ZK Hack Istanbul, and we eagerly anticipate future events that foster this level of collaboration and innovation within the zk community.

The team at o1Labs extends its gratitude to everyone who contributed to making ZK Hack Istanbul a memorable and rewarding experience. We’re especially grateful for the warm welcome and well-organized event, courtesy of Anna Rose and her team. Running a successful hackathon is no small feat, and the phrase “herding cats’’ is quite apt for Istanbul! The positive feedback from both attendees and developers was a testament to its success.

Just a glimpse of the o1Labs Team at ZK Hack: hard to believe there were even more of us behind the scenes!

Stay tuned for updates early next year as we incorporate your feedback into shaping the future of o1js! Now, we will leave you with some of the sentiments shared about o1js:

  • “Overall, the hackathon was a great experience! o1js and the tooling/docs were great to work with and I intend to keep fiddling around in my spare time.”
  • “As new as this ecosystem is, o1js is pretty great!”
  • “The ‘zk project’ project creator was awesome and made it really easy to get up and running.”
  • “Having [zkApps] developed 100% in Typescript is awesome!”
  • “Overall the usability of o1js was great!”
  • “I looked at documentation and worked through tutorials of the various projects sponsoring ZK hack, and the o1js ones were the cleanest and most thorough.”

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o1Labs is a blockchain technology company building tooling and software that leverages zero knowledge cryptography.‍

Our global team of engineers incubated the Mina Protocol, the world’s first zk blockchain, and has built o1js, the simple yet powerful framework for zk-based applications.

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