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Event Ended

Hacktoberfest Hack Day Budapest

Come along to Puzl CowOrKing this Halloween to build open-source software, explore AI and hardware, and connect with the local Hungarian dev community.

OCT 31Budapest, BudapestIn Person
Organized byJJaloliddin Ismailov

About

Join us for the official Hacktoberfest Hack Day in Budapest on Saturday 31 October!

No matter what stage you’re at in your journey, you’ll spend the day writing open-source software, exploring developer tools and generative AI, and presenting your work to your peers. You can sign up as an individual, join a group on the day, or arrive with a team of up to four people.

And since our Hack Day coincides with Halloween, we’d love you to dress up! As well as the technical project tracks, we’re holding a Best Halloween Costume competition.

Finally, in addition to the main hack sprint, developers from the local Hungarian open-source ecosystem will actively participate throughout the event. More information will be available soon.

Rules

  • Team Size: Solo or teams of up to 4 people.
  • Open Source Requirement: All projects built during the Hack Day must be published in a public GitHub/GitLab repository under an open-source licence before the submission deadline, OR consist of meaningful Pull Requests submitted to existing open-source repositories during the event.
  • Hardware Checkout: Arduino Uno Q kits are available to borrow at the organiser desk on a first-come, first-served basis for teams building hardware prototypes.
  • Demos: Every team must present a 2-minute live demo of their working code or Pull Requests at 17:30 to be eligible for prizes. No slide-only pitches.
  • Code of Conduct: All participants must abide by the official MLH Code of Conduct.

Prize Categories

3 categories
  • View Best Open-Source AI ProjectDigitalOcean

    Best Open-Source AI Project

    Exclusive Hacktoberfest 2026 Winner DEV Badge & MLH Swag Bag

    Build an original project that uses open-source or open-weight AI as an important part of how it works. Teams could create an agent skill, build with an open-weight large or small language model, or build or adapt an open-source model harness.

    Build with DigitalOceanView category
  • View Best Halloween CostumeEvent prize

    Best Halloween Costume

    Fancy figurine

    Dress up for Halloween. The person wearing the best costume will win a custom-made trophy, as decided by a live vote from the audience at the awards.

    View category
  • View Best Use of Gemma 4Deepmind Google

    Best Use of Gemma 4

    It’s time to see how much you can build with a lightweight, open model. Gemma 4 packs multimodal intelligence into an open-weights model that you can access through the Gemini API. So, what can Gemma 4 bring to your project?

    • Multimodal Experience: Work with text and images to create an assistant that understands more of what users share.
    • Focused AI Tools: Build a focused AI tool for learning, creativity, productivity, or your community.
    • Rapid Prototyping: Experiment with an open model while using the Gemini API to move quickly from an idea to a working prototype.

    Bring your idea to life… what will you build with Gemma 4 today?

    Build with Gemma 4View category

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