Open Source Software
Free and open-source DH tools
Three Digital Humanities tools we invested in: clearer documentation, easier setup, and active development. Depending on your use case, they run on our cluster and elsewhere.
The work followed a path of needs assessment, evaluation, expert workshops, and development. Per-tool working papers and an overarching evaluation paper are due from Q2 2026. Below: what each tool is, what we changed, and where to find it.
QLever
An efficient SPARQL engine for querying very large knowledge graphs (such as Wikidata), over 100 billion triples on a single standard machine, with markedly faster responses than most alternatives.
What we improved
| Before | After (DHinfra) |
|---|---|
| Steep entry barrier for new users | Quickstart & step-by-step guides |
| Docs scattered, patchy, partly outdated | Fresh, unified docs (continually expanded) |
| No standardized, reusable examples | Ready-to-use, versioned Qleverfiles |
- Documentation — completely rebuilt at docs.qlever.dev (since late 2025, continually expanded): quickstart, Qleverfile reference, troubleshooting.
- Use cases — unified Qleverfiles (24 commits since Dec 2025), publicly provided via pull request (
qlever setup-config); overview with dataset size, resources and live demos at docs.qlever.dev/use-cases. - Deployment — official packages for Debian / Ubuntu / macOS (since 21 Jan 2026); Docker images (QLever UI & Petrimaps); reproducible and tested before every release.
- DHinfra.at fork — github.com/dhinfra-at/qlever.
liiive.now
Real-time collaborative image annotation built on IIIF: annotate together, live, in the browser. github.com/rsimon/liiive (MIT licence); DHinfra.at fork at github.com/dhinfra-at/liiive.
Two ways to run it
- Hosted — no installation, instantly usable; ideal for teaching and demos.
- Self-hosted — your own server / VPS (institution or cloud) for full control over your data.
What it does
- Real-time collaboration with shared navigation and live cursor tracking
- Comments and threads on annotations
- IIIF API support and annotation export
- Anonymous sessions via a shared link, no login required
Under the hood
Browser-based web app · real-time sync over WebSockets · Supabase database · IIIF Image & Presentation API · self-hostable. Typical uses: manuscript analysis and source annotation in DH, seminars and group work in teaching, and curatorial collaboration in cultural institutions.
Pletka (formerly Zellij)
The Pletka Project (pletkaproject.org) develops an open-source platform for building and documenting semantic data models together. Projects describe their data as fields, collections and models, grounded in ontologies such as CIDOC CRM and Linked Art. From this single documentation, Pletka generates the parts an implementation needs: RDF and JSON-LD, SPARQL queries, X3ML mapping files, and files for systems such as ResearchSpace.
The core code is open source under the Apache 2.0 licence. Pletka is designed by Takin.solutions, engineered by Delving BV, and developed together with the Swiss Art Research Infrastructure (SARI, ARDEAH project) and DHinfra.at.
What we improved
| Before (Zellij) | After (Pletka) |
|---|---|
| Data held in Airtable, several bases per project | Pluggable storage on PostgreSQL, with project versioning |
| Projects set up by hand | Web admin dashboard for organizations, users, projects and pattern libraries |
| Generators behind a button | Derivatives: RDF, JSON-LD, SPARQL, X3ML and more, generated from the model |
Who it is for
Projects that model their data with CIDOC CRM or Linked Art, or build on WissKI, Arches or ResearchSpace. pletka.io holds more than 40 public models that were built with Zellij and moved over, among them Releven at the Austrian Academy of Sciences, the SARI reference data models and Linked Art. A new project can adopt and adapt these patterns instead of starting from the ontology specification.
- Code — github.com/pletka-io/pletka (Apache 2.0)
- Project and community — pletkaproject.org
- Hosted service — pletka.io