> For the complete documentation index, see [llms.txt](https://hackdays-guide.mlh.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hackdays-guide.mlh.com/start-here/readme.md).

# What Is a Hack Day?

Hack Days are small, free, entirely in-person mini hackathons powered by Major League Hacking (MLH) and our partners. They are designed to fit the scale of a professional meetup, workplace program, community workshop, or club gathering—not a full weekend hackathon.

Four to six hours is ideal, and an event may run for up to 12 hours. A Hack Day can be a workplace innovation session, professional meetup, community gathering, or student-led event; it does not need to fill an entire day.

Generative AI and other developer tools make it possible for hackers to learn, experiment, and build meaningful projects in a shorter amount of time. Unless your assigned partner category says otherwise, hackers may use any technologies that help them build their projects.

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Before applying, review [Requirements and Eligibility](/start-here/requirements-and-eligibility.md) for the complete Hack Day format and OrganizerHQ requirements.
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## What This Guide Covers

This guide contains the Hack Day-specific rules and workflows organizers need to follow, including:

* Program eligibility and required event format
* Short, copyable event schedules
* OrganizerHQ registration, check-in, project, and winner workflows
* MLH partner categories and judging requirements
* Event closeout, reimbursements, and prizes

For broader advice about building an organizing team, securing sponsorship, managing a large venue, marketing an event, or running a full-scale hackathon, use the [MLH Hackathon Organizer Guide](https://guide.mlh.com/). It is the main source for general “how to organize” guidance; this guide adds the requirements that are specific to Hack Days.

## Why Organize a Hack Day?

Hack Days give communities a low-barrier way to build together:

* **Build community.** A short, focused event helps members collaborate and meet new people.
* **Develop leadership skills.** Organizers practice project management, communication, and event planning.
* **Encourage experimentation.** Hackers can learn unfamiliar tools and turn an idea into a working prototype.
* **Access MLH support.** Approved events receive planning resources, reimbursement support, and—depending on availability—swag and prizes.

## How the Program Works

1. Confirm that your event meets the [requirements and eligibility rules](/start-here/requirements-and-eligibility.md).
2. [Apply to host](/start-here/apply-to-host.md) through OrganizerHQ.
3. Plan a focused event using the [recommended Hack Day schedule](/plan-your-event/sample-schedules.md).
4. Use OrganizerHQ for registrations, check-ins, every presenting team's project submission, and MLH partner prize winners.
5. Complete the required [event closeout](/close-out-your-event/photography.md), including photos, your event summary, and receipts.

{% hint style="info" %}
**Ready to begin?** Review [Requirements and Eligibility](/start-here/requirements-and-eligibility.md), then start your application.
{% endhint %}