OnUML is an AI diagram generator and online UML editor that brings Mermaid, PlantUML, Draw.io, and Mind Map workflows into one workspace. It supports natural-language generation, code or visual editing, live preview, repair, history, export, and sharing.

What diagram types are supported?

OnUML supports four modes: Mermaid, PlantUML, Draw.io, and Mind Map. You can create, edit, preview, and switch between them in one workspace.

How can I save my diagrams?

You can export diagrams as PNG, SVG, and other formats. If you create an account, you can also save diagrams by project for easier access, management, and continued editing later.

OnUML offers a Free plan with usage and project limits. Pro increases project and workspace capacity, while AI credits cover additional and premium AI usage.

Diagrams & whiteboards

OnUML

AI diagram generator for Mermaid, PlantUML, Draw.io, and Mind Maps

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Community votes: 0
DR by Ahrefs: 15 no change since last check

Ahrefs Domain Rating benchmarked 12 Oct 2026, rebuilt 12 Oct 2026.

OnUML metrics

Benchmarks for onuml.com: Ahrefs Domain Rating and Majestic link data, with the change since the last build.
Metric	Value
Domain Rating	15 no change since last check
Trust Flow	20 no change since last check
Citation Flow	23 no change since last check
Referring domains	93 no change since last check
External backlinks	715 no change since last check

Ahrefs Domain Rating benchmarked 12 Oct 2026, rebuilt 12 Oct 2026. Main build topic: Regional/Asia (20). Majestic benchmarked 12 Oct 2026, rebuilt 12 Oct 2026. Link data built by Majestic. Trust Flow, Citation Flow and Topical Trust Flow are trademarks of Majestic-12 Ltd.

Create and edit diagrams with AI in Mermaid, PlantUML, Draw.io, and Mind Map modes within one workspace, with live preview, export, and sharing capabilities.

What it is

Screenshot of the OnUML homepage — onuml.com, as visitors see it

OnUML is an AI-powered diagram editor that brings four diagram workflows into one workspace. Users can generate diagrams from natural language or images, then refine them through visual or code editing with live preview. The platform supports Mermaid for lightweight documentation diagrams, PlantUML for formal UML and technical modeling, Draw.io for freeform visual layouts, and Mind Map for structured brainstorming and planning.

Key capabilities include AI-powered generation, real-time diagram preview, automatic code repair for broken syntax, project-based organization, code version history, and export to PNG or SVG formats. Diagrams can be shared through shareable links, and registered users can save their work by project for easier management and continued editing.

What it is built with

AI-powered diagram generation from text and images
Multi-diagram mode support
Live preview and real-time rendering
One-click code repair for broken syntax
Code version history and restore
Project-based organization
Export to PNG and SVG
Shareable links for diagram sharing
Visual and code editing modes

Pricing

Pricing model: Freemium

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Questions from the bench

What is OnUML?: OnUML is an AI diagram generator and online UML editor that brings Mermaid, PlantUML, Draw.io, and Mind Map workflows into one workspace. It supports natural-language generation, code or visual editing, live preview, repair, history, export, and sharing.
What diagram types are supported?: OnUML supports four modes: Mermaid, PlantUML, Draw.io, and Mind Map. You can create, edit, preview, and switch between them in one workspace.
How can I save my diagrams?: You can export diagrams as PNG, SVG, and other formats. If you create an account, you can also save diagrams by project for easier access, management, and continued editing later.
What is the difference between the four diagram modes?: Mermaid is best for lightweight diagrams in documentation, PlantUML for formal UML and technical modeling, Draw.io for freeform visual layouts, and Mind Map for brainstorming and hierarchical planning.
Is OnUML free?: OnUML offers a Free plan with usage and project limits. Pro increases project and workspace capacity, while AI credits cover additional and premium AI usage.

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