What is open-ontologies?
open-ontologies is a MCP server by fabio-rovai that ontology engineering for OWL, RDF and SPARQL: validate, query, diff, lint, version and govern knowledge graphs on an Oxigraph triple store. It is listed under Knowledge & memory and has 1,080 GitHub stars.
| Type | Mcp server |
|---|---|
| Author | fabio-rovai |
| Repository | fabio-rovai/open-ontologies |
| Popularity | 1,080 GitHub stars |
| Category | Knowledge & memory |
| Security | Low risk (96/100) |
| Rank | #173 of 4,418 MCP servers; #13 in Knowledge & memory |
| License | MIT |
| Last commit | 2026-10-17 |
| Stars this week | +46 |
| Runs | Locally |
| Language | Rust |
Is open-ontologies safe to install?
open-ontologies scores 96/100 on the MCPMods security check: Low risk. No checks raised a concern. It passed 5 of 6 checks.
MCP server results come from listing signals: who publishes it, where your data goes and what it can do. The code itself is not scanned yet.
| Check | Result |
|---|---|
| Community-built server | Note |
| Runs on your machine only | Pass |
| No credentials mentioned | Pass |
| Read-only by description | Pass |
| No code execution | Pass |
| Source on GitHub | Pass |
How do I install open-ontologies?
- Find the launch command. The README says how the server starts (npx, uvx, docker or a remote URL) and which API keys it needs.
https://github.com/fabio-rovai/open-ontologies
- Add it to Claude Code. Replace the part after -- with the command from the README. Remote servers use --transport http with a URL.
claude mcp add open-ontologies -- <command from README> claude mcp add --transport http open-ontologies <server-url>
- Check it connected. This lists your MCP servers and their status.
claude mcp list
Or ask Claude to set it up
Paste this into Claude Code and it installs open-ontologies for you:
Add the "open-ontologies" MCP server from https://github.com/fabio-rovai/open-ontologies to Claude Code. Read its README for the launch command and any API keys I need, run claude mcp add, then check that it connects.