Madoc is an open-source tool developed by Digirati for the enrichment of digital objects. The primary building block for content enrichment is the International Image Interoperability Framework (IIIF), an open set of standards for sharing images and their metadata. IIIF is used by over 130 research institutions worldwide, mostly in image repositories, cultural heritage institutions, and research libraries. Participatory enrichment possibilities include annotations, translations, transcriptions, and metadata entry. In Madoc users can assemble digital collections with IIIF objects from multiple archives, libraries and museums and build an interpretative website around them. Another possibility is to run a crowdsourcing project and invite the public, researchers or students to contribute.
Madoc allows users to import IIIF objects, including metadata and the result of Optical Character Recognition (OCR). After data import, enrichment projects can be configured in the backend using a capture model or customizable template to describe entry fields. Capture models can consist of annotations to gather transcriptions, translations, entities, tags, commentaries, or metadata curation. Internal projects can be kept private, while public crowdsourcing projects allow users to participate and contribute after signing in. Submissions made by the public can easily be reviewed and validated through a user-friendly dashboard. Madoc provides a public digital exhibition space to showcase the enriched collection along with the annotations. The results of a project can also be exported using the Madoc API.
The Ghent Centre for Digital Humanities has invested in Madoc since 2019 through the Flemish consortium CLARIAH-VL. Other investors include the National Library of Wales and the Indigenous Digital Archive. We have been actively involved since the development stage and have ample experience setting up projects.
Documentation
Madoc combines a multitude of functionalities and components, both in the front-end and in the back-end. Therefore, a clear documentation page is indispensable. During CLARIAH-VL, the documentation page was significantly expanded to support developers, project managers and users. The page provides explanations, examples and screenshots, and is linked to the source code on GitHub. There is also a subpage documenting the releases of new features.
Although the documentation page is not complete, it is a tool to facilitate a wider use of the platform and strengthen the open-source character of Madoc.
Feature development
To make Madoc more user-friendly for both project managers and project participants, a range of functionalities was developed, resulting in the release of Madoc version 2.2 in October 2023. These functionalities were chosen based on comparative research and a user survey, performed in collaboration with Flemish Art Collection, meemoo and Meise Botanic Garden.
- Polygon selectors
Up until now, the Capture Model Service in Madoc only supported rectangular box selectors to define regions on the image (i.e. IIIF canvas) as the target of an annotation. Because rectangular boxes make certain projects impossible, we added the possibility to draw non-rectangular polygonal regions on the image. Digirati used Scalable Vector Graphics (SVG), following the SVG-standards defined by the World Wide Web Consortium (W3C). This selector enables more detailed annotations in Madoc.
Project participants can add an image to the viewer via a split view. This enables a comparison of different images. The dimensions of the viewer can also be adjusted to make the form more visible.
Project managers can add structured vocabularies themselves, or link to existing vocabularies. By using an auto-complete field, project participants can easily create a connection to vocabularies such as Wikidata.
Instructions for the tasks can be linked to a help button. This allows extensive instructions to be given to the project participant without overloading the form with text.
In addition to a progress bar and an overview of the collections and manifests, every project participant can access an overview of their own contributions, statistics of the other participants and updates from the project team for each project. The project landing page also allows every participant to provide feedback to the project manager(s). To enable quick and efficiënt communication, managers can send an email to all participants of the project with one click.
- Auto-save
In addition to a ‘save for later’ button, an auto-save can be enabled. In this way, a copy of the contribution is saved to the browser’s local storage every 10 seconds. If desired, the participant can restore the previous version.
The user profile provides an overview of a user’s personal information (name, e-mail address, setting, …) and the tasks they performed. The profile page also allows users to indicate for whom their personal information should be visible.
Project managers can add a page with terms of use to the project site. Each new participant is prompted upon registration to read the terms of use and agree to them. When the terms of use change, every user will be notified. Data on whether or not the terms of use are agreed to are stored and can be used to deny access to certain functionalities.
Ghent Enriched – platform for customized participation
To test and improve the technology, methodology and user experience of Madoc as a participative tool we learned a lot from the project Ghent Enriched (Gent Verrijkt), a spin-off of the cultural heritage project Ghent Mapped (Gent Gemapt) (2020-2023). Through Ghent Enriched, museums and archives offer parts of their collections and ask the public or experts to help transcribe, date, describe and identify them. Heritage partners used Madoc as a customized toolbox for digital and hybrid volunteer work. Moreover, the platform made it possible to set up shared projects with similar collections, and to learn from each other’s capture models.
We first tested the approach and technology in pilot projects. Huis van Alijn, Amsab-ISG and Archief Gent, formulated problem statements around specific collection registration cases. We then translated and implemented these cases via IIIF manifests in a capture model, and embedded the Madoc projects in existing public and volunteer operations. Students worked on the Belgian-Dutch feminist-socialist periodical De Vrouw (Woman; 1893‒1900) from the digital collections of the Belgian Amsab-Institute of Social History. They collaborated to identify all poems (over 200 in total), developed a distinct data model to describe the poems, and each conducted their own case study. An important condition of collection registration cases was to shield copyrighted collections, an advantage of Madoc.

Archief Gent made an open call for volunteers to help date the collection of 3,000 postcards of the Municipal Commission for Monuments and Townscapes (SCMS). These unique pieces contain a lot of interesting information for researchers and folklorists but have yet to be dated. Aside from historical purposes, dating is crucial for clearing copyright and thus making the postcards more accessible. The dating methodology was translated to a capture model taking into account postage and publisher stamps, writing, colours, and lay-out. After a training session on dating methodology in the archive, five volunteers individually worked on the task in Madoc. They could come back two-weekly for feedback from the archivist.
The Industry Museum uses Madoc to present and describe historical photographs of metalworking at the ACEC-site. (Former) metal workers were asked to identify machines and measuring instruments on photographs from several different companies. During a workshop with seventeen volunteers, three groups worked together with curators to complete the description of this collection and share their expertise.
Erfgoedcel Gent set up a community project to identify people and places on photographs and slides made by amateur photographer Lucien Bogaert between 1960 and 2010. People from neighbourhood de Muide are asked to further describe the collection.