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May 14th, 2025 – Boulder, Colorado

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Amid the crisp mountain air and the hum of LambdaConf 2025, something electric was happening just off the main stage: Scala developers from around the globe were diving headfirst into the first-ever ZIO Hackathon. It wasn’t just another coding sprint—it was a playground of high-concurrency, functional purity, and creative problem-solving.

Hosted as a key part of LambdaConf’s programming, the ZIO Hackathon brought together seasoned Scala veterans and up-and-coming functional enthusiasts for a full day of building, debugging, and collaborating—powered entirely by ZIO, the modern, type-safe, asynchronous and concurrent library for Scala.

The Challenge

Participants faced a series of carefully curated real-world problems designed to test both their command of functional programming concepts and their practical ability to wield ZIO’s rich ecosystem—ranging from streaming data pipelines to building resilient microservices. Contestants could pick from varying difficulty levels, from Mount Fuji, Matterhorn, and Mount Everest issues.

The Atmosphere

From the moment laptops flipped open at 9 a.m., the room buzzed with quiet intensity. Teams huddled over keyboards, sketching out effect systems, coordinating fibers, and taming resource lifecycles. Mentors from the ZIO core team circulated, offering guidance, high-fives, and the occasional cryptic hint.

There was caffeine (a lot), impromptu whiteboarding sessions, and more than a few spontaneous “aha!” moments as teams overcame deadlocks, embraced ZIO’s layered architecture, and leaned into structured concurrency.

What Made It Special

The ZIO Hackathon wasn’t just about competition—it was a celebration of the Scala community’s growth and the power of modern functional programming. Many participants noted how far the ecosystem has come, with tools like ZIO Test, ZIO HTTP, and ZIO Schema enabling rapid, production-ready development.

The challenges also reflected the real world: handling failures gracefully, composing complex services, and thinking in terms of data flow and pure transformations. And at the heart of it all was the vibrant culture of sharing knowledge and pushing each other to learn.

Take a look for yourself!

For the first time ever, we documented the process. Check part 1 of Inside ZIO Hackathon: Battle to the Top here.

Looking Ahead

If this year’s hackathon proved anything, it’s that the Scala and ZIO communities are thriving, curious, and capable of incredible things when given space to build.

Until next time—keep those effects pure and your fibers fast. 💥