Engineering Working Group/Developer Events

From OpenStreetMap Foundation

Developer events, also known as "hack days", "hack weekends" and "hackathons", are meetings of developers to discuss, network and collaborate with other developers, designers, documenters, and others with an interest in software.

In OpenStreetMap, our developer events generally involve improving OSM-related tools and software, but also experiments in using OSM data to produce interesting prototypes. These events are great for inspiring, working with and learning from other developers in the OSM ecosystem and the Engineering Working Group would love to see more of them. Please join a meeting to discuss your ideas with us!

The remainder of this page discusses the process of setting up and running an event, and the assistance available to help you achieve it.

Our recommendations

Based on our experience of hack days, we have the following general recommendations


  1. Maximize the use of wired connections, including bringing switches if necessary. Every person on a wired connection frees up wireless bandwidth, and wired is almost always faster
    • Best is to have a wired connection and switches.
    • However, if that's not possible (e.g: wired network is locked down) then using a bridge or "connection sharing" may help with wireless contention.
  2. It is not normally worth bringing shared resources like planet-latest.osm.pbf on USB flash drives as most people will not be hacking with a full planet extract on their laptop, but using a much smaller extract.
  3. Recommend people pre-install software they know they'll need and pre-download any large files they anticipate using.
  4. Use git clone --depth=1 for cloning large repos over a slow network

Facilities and administration

  1. Make the building owners/management aware that it's a hack day, not a conference and to expect everyone to have 2+ wireless devices and to be actively using 1+ at the same time
  2. Give estimates to the owner of both the number of people attending, and the percentage of additional attendees who will show up without advance notice
    • Both post-conference (e.g. SOTM) hack days and hack days unassociated with a larger event have had twice as many people attend as were registered a week before the event
  3. To expect at least 2/3rds of a 11" pizza worth of food per person
    • Be aware of dietary restrictions - some attendees may be gluten or lactose intolerant, vegetarian or require halal or kosher food. It's a good idea to either ask about this, or provide some alternatives to your "main" food item.
    • Catered food can be less flexible about changing attendance numbers
    • If ordering delivery, contact the food place well before people start getting hungry - it takes time to make a massive order.
  4. Facilities: It's always worth having;
    • A whiteboard and working whiteboard pens.
    • A projector and screen.
    • More power strips than you think you could ever possibly need.
    • A few spare international plug adaptors for loan.
  5. Double-check sufficient (allowing for last minute signups)
    • chairs
    • desk space

Organisation and promotion

  1. Timetabling.
    • We recommend having a "buffet style" event, where people are able to attend as much or as little as they like. This can be confusing, but lowers the barrier to entry.
    • People will want to turn up at whatever time suits them, so it is worth thinking about how to welcome and include them, and get them started with a project.
    • It can be useful to run workshops or tutorials, as this is a good way of giving people a help with the learning curve. Have facilities available, and think about recruiting some presenters.
    • Having an informal session after the hacking is over (e.g: dinner, drinks) is a good way for people to connect, and an opportunity to include people who might not have wanted to attend the main event. Make sure the venue is announced and, if necessary, booked well in advance of the date.
  2. Publicity. To reach the maximum number of people, we recommend:
    • Putting all the available information on the OSM wiki.
    • Putting the event details in the wiki event calendar [1]
    • Making details available on local "meet up" web services (e.g: lanyrd,, eventbrite, etc...)
    • Tweeting about it, and encouraging other local organisers, perhaps of social meetups, to retweet.
    • Asking CWG to help publicise, perhaps with a blog post.

Financial assistance

If you like the sound of a hack weekend, and would like to run your own, the Foundation's Engineering Working Group would like to help out. Sometimes it's not possible to find generous corporate sponsors for hack events, so EWG will reimburse up to US$500, or equivalent local currency, per event to help cover expenses such as space, food and refreshments. If you are interested, and would like to run a hack event, please come along to an EWG meeting and let us know what your plans are!


Before spending anything, please come along to an meeting to talk about the event. Sadly, the budget is not infinite, which means that financial assistance will not always be available. We would like to spread these events out geographically and across the year, so if you can be flexible with timing then that is a great help.

It is always worth, at an early stage, seeking out sponsors for venues. There are many companies who are willing to make such a donation in kind, and it drastically reduces the cost of running an event. If you don't know who to ask, then come along to a meeting, or ask on your local mailing list for ideas.

Try to announce your event at least one month before it happens - this allows people to organise travel or book time off work.

Please remember to collect all receipts for expenses. You will need these to get your money back. After the event is done, you can submit an expense form and we will process it as quickly as we can.

What you can expense

Things which you can expense, up to a maximum total of US$500 or equivalent:

  • Hiring a venue and costs associated with setting it up.
  • Food, snacks and other sustenance for event attendees and organisers.
  • Drinks and refreshments for event attendees and organisers.

We are open to suggestions about things which fall outside of this, rather narrow, definition: Please come talk to us about your plans. Note that, without prior approval, expenses will not be reimbursed for capital items (e.g: laptops) or travel.