The Wikimedia Hackathon Northwestern Europe 2026 is a two-day event that will take place from 13 to 14 March 2026 in Arnhem, the Netherlands. This hackathon is organized by people with extensive knowledge and experience in coding, hacking, and development, and is designed for experienced Wikimedians. The event serves as preparation for theInternational Wikimedia Hackathon 2026 in Milan and will be held fully in person and on site. Come join us for two days of coding, hacking, development, collaboration and fun!
Its flexible and open structure provides plenty of space to collaborate with other participants and share knowledge in a grassroots setting. Initiatives for collaboration on specific topics or for knowledge sharing on these days are encouraged, and space will be provided for them where possible.
Event application will start mid December and close 1 February 2026, or earlier based on event capacity. We aim for approximately 100 participants. The event is free to attend and catering (food-snacks-drinks) will be provided. Each person that attends the Hackathon is required to register.
All applications will be reviewed by the organisers to ensure that participants meet the minimum criteria and so that everyone can benefit fully from the event.
Experience & skills : Participants are expected to have an adequate level of skill and expertise in coding, hacking, and developing.
Connecting people : We also aim to create a diverse group of participants and actively encourage applications from individuals belonging to underrepresented groups.
Geography : Applicant should be from North-Western European countries
AHendriksen-collecties - wikidata and Commons: cultural heritage data (natural history and photography)
Ainali - I'll be hacking on protoypes for CommonsDB and also see if anyone has any more ideas of how a public domain registry can be used for our projects.
Audrey Penven (WMDE) - don't know yet, but I'd love to be there as a technical resource for others
BPiovesan-WMF - My goal is to better understand the needs of the volunteer developer community. If there is still a plan to develop a tool to better understand volunteer developer contributions and retention, I'd love to help think through what that might look like.
Calvinball - I would like to use WMF or WME APIs as part of a project to show how we can integrate these APIs in innovative ways to reuse data from wiki projects. I don't have a specific use case or project in mind, though.
Chaotic Enby - I would love to work on projects focused on dealing with AI (or harnessing it for good!), as well as on providing a more accessible experience for the everyday user, to help bridge the pretty steep learning curve that Wikipedia can have!
Ciell - Updates aan Jacob Olie en andere collecties uit het Amsterdam Archief.
Count Count - Tools for fighting spam and vandalism crosswiki.
CParle_(WMF) - The repohttps://gitlab.wikimedia.org/repos/structured-data/upload-tracking gathers data on uploads to Commons (and other wikis) with a view to eventually training a model to compute a likelihood-of-deletion score for uploads in order to help patrollers. I'd like to continue work on the repo - specifically to calculate and store perceptual hashes of images as they're uploaded
Cuagga - Developing further my bot, adding to it functionalities it misses for convenience of use ; coordinating with community members on the mainenance categories it could and should populate (or empty) automatically ; working on some requests to bots
Ecritures - tool to easily add IIIF collections (inclusding structured data) to Wikimedia Commons/add media files of plantations in collections of cultural heritage institutions to wikidata/Commons/resolve 8.500 urls of mediaval minitiatures to de RKD images site
Edward - Working on tools for adding links between OSM and Wikidata
Egezort - I would like to work on Rule Systems that detect problems on Wikidata and allows us to fix them.
Eugene233 - I bring with me expertise of mentorship, toold development and also my experience volunteering in the PTAC for the Foundation to not only work on projects which i contribute to or I collaborate on, but also engage in discussions on how the Wikimedia technical community can better address the needs of the global community in terms of providing support. As one of the organizers of the Wikimania hackathon this year, I look forward to engaging discussions how the wikimania hackathon can be designed to support participants from the European communities either on-site or online.
Geertivp - How to make use of Pywikibot and related tools to automate amending MediaWiki platforms, and controlling the quality of the content.
Husky - Probably a tool i'm in the planning stages of right now to make WD editing easier
Ideophagous - Continue developing DarijaBot (especially category automation), prepare the next batch(es) of quickstatements (statistics of Moroccan villages, biographies)
ItsNyoty - I would like to work further on TBx Manager as main contributor since it hasn't had any real updates and is still in Beta on nlwiki
Jean-Frédéric - I have plans to work on integraality. I have several ideas for new features, which are on the Phabricator board [1] (if there are users there I would love to have their input). But especially as there will be other Toolforge users and experts I am thinking of the following tasks:
move the repository and CI to Wikimedia Gitlab
use Toolforge build service for deployment
implementation of an asynchronous job-based system using Celery and Toolforge Redis (not sure how well that would work, would definitely need some help ^_^)
I also have been putting off upgrading my deployments − Mirador is 2 major versions behind, and there is new framadate upstream for Wudele − that could be a fun project.
Malyacko - I could probably answer Phabricator, development statistics, and most deployment questions, and help bring contributors together. I'd probably hack on Phabricator code.
Matma Rex - I don't have specific plans yet. I can be available to help anyone who needs advice regarding MediaWiki.
Mehman - I will be working on improving editing gadgets for Wikipedia and on modules for integrating Wikidata into Wikipedia.
Nivopol - I keep thinking we would benefit to work on a usable federated calendar, and now we have the new Campaign Events system providing kind of a generic list to add to the various calendar systems. I would say Cronos stays a good bet even if federation is not priority subject. I would also like to contribute some Lua automation for Wikisource, as, for instance, a way to create on an Index: discussion page a summary of discussion made on all Page: discussion page for a book or a book series. Any idea to help contributors using coherent choices for a whole opus is welcome. About the Campaign Events/Event registration system, I think the contribution monitoring page could be better for wikisource metrics (like using the Page: page status). I would also be glad to help on wikisource proofread statistics bot and display.
Nonoxb - I am particularly interested in the wiki parser, Wikisource tools and Wikidata integration into Wikipedia. I would also like to understand better how Toolforge works so that I can deploy tools in the most efficient way
OlafJanssen - Probably Wiki-AI-related stuff, got about 20 projects to choose from.
Olea. I'm considering alternatives all around Wikibase, depending the interest of collaborators we could take one or another way
integration of Wikisource features into Wikibase Suite;
a proof of concept for a preconfiguration ofExtension:WikibaseQualityConstraints in Wikibase usingcrm4wb, for example for implementing OWL restrictions in a ontology for range and domain.
Oliebolw001 - During the event I want to work on TBx Manager together with 2 colleagues of mine. I also look forward to working with others and meeting everyone.
RonnieV - Sharing thoughts, inspiring others, working on how to organize things, getting support
RThomas-WMF - Platform reliability, infrastructure and tooling improvements, observability and automation, and contributing an SRE/architecture perspective to ongoing Wikimedia technical projects.
Simon04 - Experiment with MultimediaViewer improvements/rewrite and/or any map related tool.
Sjoerddebruin - Improving or making scripts that lower backlogs on various projects
So9q - I'm currently working ona new scalable backend for Wikibase. If you have a cool project you would like me to help with, then feel free to contact me :)
Spinster - Continuation of work on Rijksmonumenten and/or maybe a Wikidata-driven website on (cultural) awards, or other things that the group is working on as well.
Sukkoria - My main idea is to work on a current personal project, which would be a tool to parse batches of museum labels’ pictures to retrieve metadata about the works (using Optical Character Recognition) and help automate their import into Wikidata with tools such as OpenRefine. I’ll likely end up working on it at some point in the future because I’m really lagging behind on my pictures to be imported! Other ideas include:
improving the "reading interface/experience" on Wikipedia by adding info about the freshness of the articles, the inspiration being the messages "This article is X years old and may be outdated" that can be found of some news sites. This would be built using MediaWiki APIs and display the "time since last edited by a human" -> that could also prompt editors to improve outdated articles
anything about data quality on wikidata: constrains checks, data quality frameworks (great_expectations, but for wikidata?), or using external open data to validate and improve Wikidata content (cf. Osmose for OSM)
anything about data visualisation on-wiki: timelines (band members is something I’d like to explore "one day"), new charts extensions and how to make them more usable for less technical contributors
T Arrow - I'd like to find other people and projects to help unblock people. I'd be happy to maybe do something towards sparql or the rest API. Maybe also I can help with some DevOpsy / media wiki on kubernetes stuff to help with.
Theklan - I would like to advance in visualizations using the new Chart syste, and also other things like OurWorldInData. I'm trying to upload demographic information from Modules in frwiki to Commons and/or Wikidata.
TheresNoTime - I would like to work with newer developers to help them onboard to our codebase and help with merging things on gerrit/deploying where appropriate
Tsaag Valren - vulgarisating and simplifying. There is a real need for this because we have so many great tools that are impossible to understand for the majority of contributors who are not developers.
Valhallasw - I'd like to pair up with someone with less technical expertise (e.g. someone from a GLAM background) to figure out how to get information into WM projects (could be Commons, could be something with a bot on WP, could be Wikidata). Would also like to see if we can get make more roller derby content available. Would also like to see what I can do to make the projects I'm still responsible for more community-supported (documentation, knowledge handover, etc)
Rozet is wheelchair accessible, with a ground-level entrance, lifts to all floors, and accessible toilets. There is a quiet space available for relaxation or sensory relief.
Arnhem can be reached by national trains as well as by the ICE International from Germany. A Flixbus stop is located next to Arnhem Central Station (Amsterdamseweg 13). Rozet is approximately a 10-minute walk from Arnhem Central Station.
Grey building on the left is the hotel (Holiday Inn Express)
WMNL can arrange hotel accommodation (at the Holiday Inn Express Arnhem by IHG) for participants. Please note thatsingle rooms are limited. We strongly encourage you to share a twin room or arrange your own accommodation.
Shared Rooms: You may name a preferred roommate during registration. Please coordinate with them beforehand to ensure the request is mutual.
Coverage & Dates
Standard Coverage: WMNL covers the cost oftwo nights (Check-in: Thursday, 12 March | Check-out: Saturday, 14 March).
Extra Nights: You may extend your stay at your own expense, in the same room type as indicated in the application form, for a single night. WMNL will invoice you for the additional night.
Single Room: ~€150.00
Double Room: ~€155.00 (total cost)
Professional Attendees If you are attending on behalf of an employer or organization, we kindly ask that you check if they can cover your accommodation costs. WMNL will provide an invoice for your organization.
Please note that WMNL doesnot offer travel scholarships or cover travel expenses. We encourage participants to first contact their local chapter for support. In specific cases a small, limited budget is available for international travel through WMNL. If you think you may be eligible, please contact Lisa.Hackathon[@]wikimedia.nl.
The programme is shaped with input from the community, encouraging a grassroots approach and a strong sense of ownership among participants. As an unconference, it is a participant-driven event in which the agenda is created by the attendees themselves. Rather than following a fixed programme with predefined speakers, participants propose topics on the spot and take an active role in leading discussions. This format encourages open exchange, collaboration, and equal participation, making it especially suitable for sharing ideas, experiences, and questions in an informal setting.
Maarten Dammers presenting at Provenance Loves Wiki 2024Annika Hendriksen at WikiconNL 2025Siebrand Mazeland at the Wikimedia Hackathon 2025Daan van Ramshorst at WikiconNL 2025
The event is organised by:
Maarten Dammers - Maarten, known in the community as Multichill, is a long time Dutch developer and Wikimedia volunteer specializing in technical support for the GLAM sector. A key driver behind initiatives like Wiki Loves Monuments and the "Sum of All Paintings" project on Wikidata, he builds tools and operates bots to facilitate large-scale media uploads and data integration. In addition to his background as a network engineer, Maarten is an experienced event organizer who has coordinated numerous technical gatherings, including the Wikimedia Hackathon 2013 and the upcoming Wikimedia Hackathon Northwestern Europe 2026 in Arnhem.
Annika Hendriksen - Annika, known as AnnikaHendriksen on Dutch Wikipedia (particularly highlighting Dutch female photographers on Dutch Wikipedia), is a Dutch photo historian, working as information developer at Naturalis, and organizer in the Wikimedia community. With a professional background as a curator in Delft and project coordinator & data manager at the Naturalis Biodiversity Center in Leiden, she specializes in connecting cultural heritage and natural history collections with open knowledge platforms. Her Wikimedia contributions focus heavily on GLAM initiatives (as user AHendriksen-collecties), and biodiversity data, f.e. on Research Expeditions. As an organizer for technical events, including the Wikimedia Hackathon Northwestern Europe 2026 and the recurring Mini Hackathons in Utrecht, she bridges the gap between content specialists and developers to facilitate digital heritage innovation.
Siebrand Mazeland - Siebrand is a long time volunteer and technical contributor to the Wikimedia movement based in the Netherlands, specializing in internationalisation and localisation to ensure all Wikimedia projects support many languages. He serves as the Community Manager for translatewiki.net, supporting thousands of volunteer translators, and is actively involved in organizing development and coding events within the Wikimedia movement.
Daan van Ramshorst - Daan, known in the community as Daanvr, is a freelance creative technologist and Wikimedia volunteer based in the Netherlands. Specializing in Wikidata, open-source development, and AI-driven tools, he focuses on leveraging technology to enhance digital heritage and open knowledge. Daan is a frequent contributor to Wikimedia Commons and Wikidata, often working on projects that involve data visualization and GLAM partnerships, such as the Open Topstukkenproject. In addition to his technical contributions, he is an active community organizer, serving on the organizing team for the Wikimedia Hackathon Northwestern Europe 2026 and the Mini Hackathon October 2025 in Utrecht.
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