Open Knowledge Graphs

Open Knowledge Graphs is a static, daily-refreshed catalog of ontology and semantic software records sourced from Wikidata. It publishes both machine-readable artifacts (Turtle + JSON) and a searchable browser UI.

Live Links

• Site: https://openknowledgegraphs.com/
• Semantic Search API: https://api.openknowledgegraphs.com/
• Ontology schema (Turtle): https://openknowledgegraphs.com/ontology.ttl
• Ontologies dataset (Turtle): https://openknowledgegraphs.com/data/ontologies.ttl
• Ontologies dataset (JSON): https://openknowledgegraphs.com/data/ontologies.json
• Software dataset (Turtle): https://openknowledgegraphs.com/data/software.ttl
• Software dataset (JSON): https://openknowledgegraphs.com/data/software.json

API

Semantic search over the full catalog.

GET https://api.openknowledgegraphs.com/search?q=movie+ontology&limit=5
GET https://api.openknowledgegraphs.com/ontologies?q=healthcare+vocabulary
GET https://api.openknowledgegraphs.com/software?q=rdf+triplestore

Parameters: q (required), category, type (ontology|software), limit (default 20, max 100)

Categories: Life Sciences & Healthcare, Geospatial, Government & Public Sector, International Development, Finance & Business, Library & Cultural Heritage, Technology & Web, Environment & Agriculture, General / Cross-domain

Architecture Overview

1. scripts/fetch_data.py queries Wikidata (WDQS), normalizes records, and writes:
   • data/ontologies.ttl
   • data/ontologies.json
   • data/software.ttl
   • data/software.json
2. Category enrichment is maintained in data/categories.json:
   • one-time backfill: scripts/classify_categories.py
   • incremental on daily refresh: scripts/fetch_data.py
3. site/index.html + site/app.js + site/style.css render the client-side catalog UI.
4. GitHub Actions refresh data daily and deploy the static site + datasets to GitHub Pages.

Repository Layout

• data/: published datasets and category mappings
• scripts/: data refresh and LLM classification scripts
• site/: static frontend (HTML/CSS/JS + assets)
• .github/workflows/: CI/CD for data refresh and Pages deploy
• ontology.ttl: ontology and SHACL shape definitions

Local Setup

Prerequisites

• Python 3.11+ (3.12 recommended)
• pip

Install

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Refresh Data Locally

python scripts/fetch_data.py

Optional category backfill (Anthropic):

export ANTHROPIC_API_KEY=your_key_here
python scripts/classify_categories.py

Run the Site Locally

python -m http.server 8000

Then open: http://localhost:8000/site/

Data API Documentation

There is no server-side API; the JSON files are the API surface.

ontologies.json

Top-level object:

{
  "generatedAt": "2026-03-08T03:21:55Z",
  "items": []
}

items[] fields:

• Required:
  • title (string)
  • wikidataId (IRI string to Wikidata page)
  • types (string array, may contain multiple values)
• Optional (omitted when absent):
  • description (string)
  • homepage (IRI string)
  • partOf (string)
  • licenses (string array)
  • category (string, one of predefined domain categories)

software.json

Top-level object:

{
  "generatedAt": "2026-03-08T03:21:55Z",
  "items": []
}

items[] fields:

• Required:
  • title (string)
  • wikidataId (IRI string to Wikidata page)
  • types (string array)
• Optional:
  • description (string)
  • homepage (IRI string)
  • licenses (string array)
  • latestVersion (string)
  • releaseDate (ISO date string)

Ontology Documentation

Schema source: https://openknowledgegraphs.com/ontology.ttl

Classes

Class	Description
okg:Resource	Base class for all catalog resources
okg:Ontology	Ontology resources
okg:ControlledVocabulary	Controlled vocabulary resources
okg:Taxonomy	Taxonomy resources
okg:Software	Software/tooling resources
okg:License	License nodes attached to resources

Core Properties

Property	Range	Notes
okg:title	xsd:string	required; max 1
okg:wikidataId	IRI	required; max 1
okg:description	xsd:string	optional; max 1
okg:category	okg:Category	optional; max 1
okg:homepage	IRI	optional; max 1
okg:hasLicense	okg:License	optional; multi-valued
okg:partOf	xsd:string	optional; max 1
okg:latestVersion	xsd:string	software only; optional; max 1
okg:releaseDate	xsd:date	software only; optional; max 1
okg:licenseName	xsd:string	license node label

SHACL constraints are defined in okg:ResourceShape, okg:SoftwareShape, and related shapes in ontology.ttl.

CI/CD Pipeline

Data Refresh Workflow

File: .github/workflows/update-data.yml

• Trigger: daily at 0 6 * * * (06:00 UTC) + manual dispatch
• Installs Python dependencies
• Runs python scripts/fetch_data.py
• Commits changed data files as github-actions[bot] with:
  • chore(data): refresh catalog from Wikidata

Deployment Workflow

File: .github/workflows/deploy.yml

• Trigger: pushes to main affecting site/**, data/**, ontology.ttl, or workflow file
• Builds Pages artifact from:
  • site/ (frontend)
  • data/ (datasets)
  • ontology.ttl (schema)
• Deploys via GitHub Pages actions

Fork and Deploy

1. Fork the repository.
2. In your fork, enable GitHub Pages with source set to GitHub Actions.
3. (Optional) Configure a custom domain:
   • add site/CNAME
   • set DNS records
   • enable HTTPS in Pages settings
4. If using category classification, add ANTHROPIC_API_KEY as a repository secret or environment variable for the workflow runtime.
5. Run Update Catalog Data manually once to generate/refresh data.
6. Push any change to site/, data/, or ontology.ttl to trigger deploy.

Migration from Streamlit

The Streamlit app has been removed from main (app.py no longer exists). See the full migration and feature mapping guide:

• docs/MIGRATION.md

Legacy reference data model remains available in dist/catalog.ttl (ignored in git).

Troubleshooting

• fetch_data.py fails with HTTP/timeout errors:
  • rerun; the script has retry/backoff for WDQS throttling
• No category assignments added:
  • confirm ANTHROPIC_API_KEY is set
  • run python scripts/classify_categories.py manually
• Site loads but data is empty locally:
  • serve from repo root and open http://localhost:8000/site/
  • verify data/*.json exists and is valid JSON
• Workflow runs but no commit is created:
  • no data diff detected in tracked outputs

FAQ

Is this only open-source software?

No. The catalog includes both open and proprietary resources if they are represented in Wikidata.

Are records manually curated?

Primary metadata is sourced from Wikidata queries. Category labels can be added via LLM classification and then frozen in data/categories.json.

Why do some fields appear missing?

Wikidata coverage is uneven. Optional fields (homepage, license, version, release date, category) are omitted when unavailable.

How often is data refreshed?

Daily at 06:00 UTC via GitHub Actions, plus manual runs.

Contributing

See CONTRIBUTING.md for contribution workflow and quality checks.

Data and License

• Data source: Wikidata (CC0)
• Code license: MIT (see LICENSE)