ArchGPT vs OnUML
ArchGPT
archgpt.inOnUML
onuml.comSide by side
| Figure | ArchGPT | OnUML |
|---|---|---|
| Price from | ₹499/mo | $8/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| API | — | Yes |
| Plans published | 3 | 5 |
| Spec score · AI Diagram Generators | 8.2 (#10) | 7.7 (#20) |
| Editing | Generated diagrams can be edited in the built-in Draw.io editor. | Users can edit diagrams visually or through code and preview changes in real time. |
| Product | ArchGPT converts plain-English descriptions into professional diagrams that users can download, edit, and share. | OnUML is an AI diagram generator and online UML editor for Mermaid, PlantUML, Draw.io, and mind maps. |
| Support | The contact page says the team typically replies within 24 hours. | 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
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.