Side by side
PlyDB vs Stardog
Both stand on data federation software. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Choose PlyDB if you want AI agents to query live sources with SQL while the data stays in your infrastructure. Its cross-source queries, local operation, and read-only default make it a fit for the listed operational and business analysis use cases. The CLI requires shell access, and MCP configuration changes require a server restart.
Visit PlyDB
Stardog offers data virtualization, semantic querying, and knowledge-graph tools across several deployment options. The free plan is commercially usable, but omits several capabilities and limits stored edges.
Visit StardogThe facts
| PlyDB | Stardog | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | No |
| Runs on | Linux, Mac, Windows | Android, API, iPhone, Linux, Mac, Self-hosted, Web, Windows |
| Lowest paid plan | Not published | Free or on request |
| Plans published | None | 4 |
| Maker | Not published | Not published |
| Website | plydb.com | stardog.com |
| On data federation software | #14 of 24 | #10 of 24 |
PlyDB: what it does well
- Joins data across sources in one SQL query.
- Queries connected sources directly without staging data.
- Runs locally; only query results go to the AI agent.
- Read-only by default, with writes requiring explicit permission.
- Free and open source under Apache 2.0.
What to know first
- The CLI requires shell access.
- MCP must be restarted to pick up configuration changes.
- Apache Iceberg and Delta Lake support is planned.
Stardog: what it does well
- Virtualizes data without moving or copying it
- Applies business rules during queries
- Supports SPARQL, GraphQL, and W3C RDF
- Runs in managed cloud, customer cloud, or on premises
- Free commercial plan includes up to three databases
What to know first
- Free plan is limited to 1 million stored edges
- Free plan excludes high availability and backups
- Free plan excludes LDAP and the full breadth of Connectors
Alternatives to PlyDB Alternatives to Stardog The whole list