Ontology Viewer for VS Code
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Explore OWL, RDF, RDFS, and SKOS as a readable schema diagram without leaving VS Code. Ontology Viewer combines a polished, searchable canvas with safe Turtle editing, so the diagram is useful for both understanding an ontology and shaping it.
Ontology Viewer is in preview. Keep source control enabled for important ontologies and review diagram-generated changes before committing them.
Why you will enjoy using it
- Readable schema cards keep datatype properties inside their class instead of turning every triple into visual noise.
- Accessible, meaningful colors automatically choose readable node text and explain how related entities form color families.
- A spacious, zoomable canvas includes zoom in/out, reset to 100%, fit-to-screen, layout switching, and PNG export.
- Fast navigation searches classes, relations, and properties. Double-clicking a node focuses its neighborhood.
- SPARQL queries run against the open ontology, entirely on your machine, with results shown as text and reflected on the diagram (highlight matches or filter out the rest).
- An adaptive Inspector stays beside the graph on wide screens and becomes a dismissible sheet in narrow editor groups.
- Safe Turtle write-back re-parses every generated edit before accepting it. Create classes and relations, rename entities, and edit properties or descriptions directly from the diagram.
- English and Japanese UI follows the VS Code display language.
- Local-first operation sends no ontology contents or usage telemetry from the extension.
Get started in one minute
- Install Ontology Viewer from the VS Code Marketplace.
- Run Ontology Viewer: Create Sample Ontology... from the Command Palette, or open a
.ttl file.
- Press
Cmd+Alt+O on macOS or Ctrl+Alt+O on Windows/Linux. You can also use the diagram button in the editor title bar.
- Select a class to inspect it. Use the floating canvas controls to zoom or fit the graph.
- For Turtle files, edit the selected class in the Inspector and review the source change in the editor.
Continue with the Getting Started guide or the hands-on tutorials.
What you can do
Explore
- Switch between a class-focused Schema view and a raw Triples view.
- Search and focus entities, inspect incoming and outgoing relations, and see entity/relation/property counts.
- Drag nodes into a useful arrangement; positions are remembered per file and view when you reopen the diagram.
- Choose the organic
fcose layout or layered dagre layout.
- Export the current diagram as PNG or its saved layout as JSON.
Query with SPARQL
Open the SPARQL panel from the toolbar to run SPARQL 1.1 queries against the ontology you have open. SELECT, ASK, and CONSTRUCT/DESCRIBE are supported. Press Run or Ctrl/Cmd+Enter to execute.
New to SPARQL? The panel ships nine example queries that work on any ontology, ordered from "show me anything" up through OPTIONAL, FILTER, aggregation, ASK, and CONSTRUCT — pick one and run it. The SPARQL tutorial walks through them.
Results show as text — a table of bindings for SELECT, a boolean for ASK, or subject/predicate/object rows for CONSTRUCT — and are reflected on the diagram:
- Highlight accents matching nodes and their connecting edges while keeping the rest of the graph visible.
- Filter dims everything the query did not match, and composes with the search box and double-click focus.
- No graph effect shows the text result only.
Queries execute locally in the extension host (powered by Comunica); no ontology contents leave your machine.
Edit safely
Turtle files support diagram editing. You can create classes and relations, rename entities, add/rename/retype/delete properties, and edit descriptions. Every write is applied to an in-memory candidate and re-parsed first. If verification fails, the source file is left unchanged.
Text editing remains first-class: Turtle also has outline, hover, completion, and Rename Symbol (F2) support.
Bring existing ontologies
RDF/XML and JSON-LD are viewable directly. Use Ontology Viewer: Convert to Turtle for Editing... when you want diagram write-back. The conversion creates a new document and does not overwrite the source file.
| Format |
Extensions |
Diagram |
Edit from diagram |
| Turtle |
.ttl, .turtle |
Yes |
Yes |
| TriG |
.trig |
Yes |
No |
| N-Triples |
.nt |
Yes |
No |
| Notation3 |
.n3 |
Yes |
No |
| RDF/XML / OWL/XML |
.rdf, .owl |
Yes |
Convert first |
| JSON-LD |
.jsonld |
Yes |
Convert first |
SPARQL querying works on every format in this table — it runs against the parsed triples, so no conversion is needed. Only writing back is Turtle-only.
See Format Support for parser and editing details.
Commands
| Command |
Default keybinding |
| Ontology Viewer: Open Diagram Preview |
Cmd+Alt+O / Ctrl+Alt+O |
| Ontology Viewer: Convert to Turtle for Editing... |
— |
| Ontology Viewer: Export Diagram Layout as JSON... |
— |
| Ontology Viewer: Create Sample Ontology... |
— |
Cmd+Shift+O / Ctrl+Shift+O remains VS Code's built-in Go to Symbol in Editor command.
Settings
| Setting |
Default |
Description |
ontologyViewer.preview.autoRefreshDebounceMs |
300 |
Delay in milliseconds before a source edit refreshes the diagram. |
ontologyViewer.preview.defaultView |
schema |
Initial view: schema or triples. |
ontologyViewer.preview.layout |
fcose |
Automatic layout: fcose or dagre. |
Documentation and help
Before opening an issue, check the troubleshooting guide. Bugs and focused feature requests are welcome in GitHub Issues.
Privacy and trust
Ontology Viewer processes ontology documents locally in the VS Code extension host and webview. The extension does not include telemetry, advertising, accounts, or an extension-owned network service. See the Privacy Notice for the exact data flow and the Security Policy for reporting vulnerabilities.
License
Released under the MIT License. Bundled dependency notices are listed in THIRD_PARTY_NOTICES.md.
