1 OCTOBER TO 31 OCTOBER 2026 · GLOBAL ONLINE BUILD · BUDAPEST
Build open technology that makes the systems we depend on more secure, more efficient or more resilient.
Your problem. Your stack. Your approach. No prescribed implementation.
01 / THE BRIEF
Choose a real problem and build an open technical response.
HACK4EARTH does not ask everyone to build the same thing. We want to see whether your work makes an important system meaningfully better, and whether someone else can inspect, learn from or reuse what you built.
02 / BUILT ON 2025
THE FIRST HACK4EARTH · GREEN AI
The first HACK4EARTH focused on Green AI while the field itself was still taking shape.
Participants built independently, learned in public and submitted open technical work. In 2026, we keep that experimental spirit and open the field wider across secure, efficient and resilient systems.
“I learned a ton by diving deep into the project and working through challenges on my own. I really appreciated how welcoming of beginners the experience was. It made it feel approachable.”
PAST PARTICIPANT RECOGNITION
Participants who completed a submission in the previous edition received a HACK4EARTH digital Holopin sticker as part of their participant recognition.
View the HACK4EARTH Holopin sticker ↗03 / THREE OPEN TRACKS
One winner from each track advances to TraceLab.
01 / SECURE
Cybersecurity · privacy · cryptography · software supply chain · post-quantum
Build open software that makes important digital systems harder to compromise, easier to audit or safer to operate.
Possible directions include security tooling, privacy infrastructure, post-quantum migration, secure communications, supply-chain integrity and IoT security.
02 / EFFICIENT
Green software · compute · cloud · data · AI efficiency · hardware
Build open software that delivers useful work with fewer computing resources.
Possible directions include efficient algorithms, cloud optimisation, smaller AI systems, memory and storage reduction, hardware-aware software and efficient data processing.
03 / RESILIENT
Food · water · energy · climate · communications · infrastructure
Build open technology that helps important systems continue functioning under environmental, infrastructure or resource pressure.
Possible directions include agriculture, water, energy, communications, environmental monitoring, climate adaptation, offline-first technology and fault-tolerant infrastructure.
04 / THE PRIZE
3 TRACKS · 3 WINNERS · TRACE LAB
The winning team from each track earns a place in TRACE LAB · the 3-Month Venture Lab.
TraceLab is a competitive continuation stage designed to help promising HACK4EARTH projects leave the hackathon and encounter the real world.
Technical, product and sector guidance across the three months.
Access to emerging technical talent and intern support where appropriate.
Pressure-test the idea against users, organisations, environments and practical constraints.
Funding readiness, applications, introductions and opportunities where available.
Strengthen documentation, project structure, governance and usability.
Explore deployment, partnership, venture or further incubation pathways.
05 / OCTOBER
All times are Budapest local time.
Tracks open and the build month begins.
Interactive online events, technical demos, community sessions and surprise drops. Selected activities will offer chances to win swag and prizes.
Two-hour HackDay, technical demos, guest talk and giveaway at Eco-Office, with a YouTube viewing option. View the programme ↗
Submissions for all three core tracks close on Saturday night.
06 / LIVE PROGRAMME
The live programme adds technical energy without turning the month into a classroom.
See tools, technologies and open projects in action.
Short sessions with engineers, researchers and practitioners.
Meet teams, show work in progress and exchange ideas.
Selected activities may include tools, credits, swag and smaller prizes.
07 / SATURDAY · 31 OCTOBER · BUDAPEST
50 IN-PERSON PLACESHACKTOBERFEST · GREENER FIELDS
Two hours of open source, practical ideas and builders who care what their technology makes possible.
11:30–13:30 CET · Eco-Office, Izabella u. 68/b, 1064 Budapest, Hungary
Present the October challenge, explore the themes and get hands-on. Explore the challenge ↗
Community demonstrations and curated reviews of open-source technical projects.
Ten minutes, one perspective worth sharing.
HackDay winner announced and prizes presented.
One challenge winner takes home a belt bag, T-shirt and PVC sticker. Eligible participants can follow the HoloPin badge-claim instructions.
In-person seats are limited. Register on MLH in advance and bring your check-in PIN to the venue. The HackDay giveaway is separate from the three HACK4EARTH competition tracks, which close for submissions later that evening.
08 / ONLINE FROM BUDAPEST
You don't have to be in the room to be part of the conversation. Join our Hacktoberfest closing HackDay online as we explore greener, more secure and more resilient open-source technology.
09 / PEOPLE + COMMUNITIES
HACK4EARTH brings together local green-software organisers, AI community builders and the global open-source movement.
Organised by Data Immigrant Kft in Budapest.
Meet the community ↗Our Budapest group is part of the Green Software Foundation's community network.
Official foundation website ↗Budapest community ↗Our organising team also serves in a Google AI Community organiser role.
Powered by Major League Hacking (MLH) and DEV; presented globally by DigitalOcean.
Hacktoberfest ↗Community connections and global Hacktoberfest programme credits are shown for context; they do not imply direct sponsorship of this local event by every organisation named.
10 / SUBMISSION
Prototype, tool, library, system, experiment or technical implementation.
Source code plus enough documentation for someone else to understand the work.
Show the project working clearly and concisely.
What was technically difficult, interesting or original about your approach?
Show what became safer, more efficient or more resilient.
11 / JUDGING
Does it work? Is the engineering credible? Can someone reproduce it?
Does it meaningfully improve the system or problem it addresses?
Why does the work matter for resources, infrastructure, environment or resilience?
HACK4EARTH 2.0 · OCTOBER 2026
Three tracks. Three winners. Three months to find out what the project could become.
Register to participate