| Price from | — | Free |
| Free plan | — | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | — | Yes |
| Android | — | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 0 | 5 |
| Spec score · Data Virtualization Software | 7.9 (#11) | 8.4 (#7) |
| Spec score · Knowledge Graph Software | 7.8 (#20) | 8.4 (#11) |
| Deployment | Ontop can be deployed as a SPARQL endpoint using its command-line interface or Docker image. | Stardog can run as a managed AWS cloud service, in customer cloud environments, or on premises through Docker, Kubernetes, AWS Marketplace, and Azure Marketplace. |
| Headquarters | Bolzano, Italy | New York, New York, United States |
| License | Ontop is available under the Apache 2.0 license. | Stardog Free is proprietary, licensed software and the pricing FAQ explicitly says it is not open source. |
| Purpose | Ontop exposes relational database contents as virtual knowledge graphs and translates SPARQL queries into SQL queries executed by the source databases. | Stardog connects enterprise data into a semantic layer for AI, analytics, search, and applications. |
| Standards | It uses RDF 1.1, supports RDFS and OWL 2 QL ontologies, and supports R2RML and Ontop mappings. | The platform supports SPARQL, SPARQL*, GraphQL, and W3C RDF standards. |
