AI Diagram Maker vs OnUML
AI Diagram Maker
aidiagrammaker.comOnUML
onuml.comSide by side
| Figure | AI Diagram Maker | OnUML |
|---|---|---|
| Price from | $10/mo | $8/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| API | Yes | Yes |
| Plans published | 3 | 5 |
| Spec score · AI Diagram Generators | 9.3 (#1) | 7.7 (#20) |
| Credit limits | Each credit represents 1,000 tokens, credits reset monthly on the billing-cycle date, and users who run out currently must wait for the reset. | Purchased AI credits expire 6 months after issuance and do not unlock diagram, project, or workspace capacity. |
| Integrations | The MCP server works with Cursor, Claude Desktop, Claude Code, and other MCP-compatible clients. | Its remote MCP server connects to coding agents including Codex, Claude Code, Cursor, and OpenClaw. |
| MCP access | The MCP server uses API keys from an AI Diagram Maker account, which users can rotate or revoke in settings. | The MCP server follows the signed-in account’s workspace permissions and supports reading and updating Mermaid, PlantUML, and OnUML mind maps; Draw.io is not supported through MCP. |
| Product | AI Diagram Maker creates software architecture and flow diagrams through a conversational interface. | OnUML is an AI diagram generator and online UML editor for Mermaid, PlantUML, Draw.io, and mind maps. |
| Support | The contact page directs users to its Discord community for support, while Plus and Max plans include priority support. | The site lists [email protected] as its contact email. |
Plans
OnUML
- FreeFree
- Starter$4.90, paid once
- Pro$8 a month
- Popular$9.90, paid once
- Pro Pack$19.90, paid once
In their own words
AI Diagram Maker
AI Diagram Maker has no write-up on Specifiction yet; its figures are above.
OnUML
OnUML is a web-based AI diagram generator and UML editor for Mermaid, PlantUML, Draw.io and mind maps. It creates diagrams from natural-language prompts and supported image inputs, then supports visual or code editing with a real-time preview. A one-click repair tool addresses Mermaid and PlantUML syntax errors. Users can save multiple code versions, restore earlier content and organize diagrams by project. PNG and SVG export and shareable links are supported. Its remote MCP server connects with coding agents including Codex, Claude Code, Cursor and OpenClaw. MCP follows workspace permissions and can read or update Mermaid, PlantUML and OnUML mind maps; Draw.io is excluded. It checks for newer edits before updates and stops if an overwrite would occur. The Free plan costs nothing, billed forever, with two diagrams per project, ten cloud projects per workspace, two workspaces and ten free model requests daily. Paid choices include 4.90 USD and 9.90 USD one-time plans, a 19.90 USD one-time Pro Pack and Pro at $8 a month.