UML Diagram Tool

A free online UML diagram tool for developers, educators, and teams to create, edit, and share UML diagrams without installing software.

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About This Tool

This tool provides a browser-based UML modeling workspace that supports multiple UML diagram types: class, sequence, activity, and use-case diagrams. It enables teams to model software structure and behavior without desktop software. The domain logic treats diagrams as graphs: nodes represent UML elements and edges represent relationships; the editor enforces semantic rules and offers guided templates.
Users define the diagram scope, add elements such as classes or lifelines, and establish relationships like associations or messages. Real-time validation ensures conformance to UML semantics and auto-layout positions elements for readability. The platform stores the diagram model in the cloud, enabling collaboration, versioning, and easy sharing. Unique value comes from template-driven diagrams, constraint awareness (multiplicities, visibility), and seamless export to common formats for documentation or tooling pipelines. Typical use cases include API design with class diagrams, system behavior through sequence diagrams, and workflow modeling via activity diagrams. The tool focuses on modeling accuracy, team collaboration, and rapid iteration without requiring local software installation.

How to Use

  1. Provide inputs: select diagram type and define the diagram scope.
  2. Add elements: create classes, lifelines, or actors depending on the type.
  3. Establish relationships: connect elements with associations, messages, or flows.
  4. Validate & layout: run automatic validation and auto-layout to position elements.
  5. Export or share: save as SVG/PNG/PDF or generate a shareable link.
How to use free online uml diagram tool

Frequently Asked Questions

Find Quick Answers

What diagram types are supported?
The tool supports class, sequence, activity, and use-case diagrams. It preserves UML semantics for elements and relationships, enabling accurate modeling and easy translation to documentation or code structures.
Can I collaborate with others?
Yes. Diagrams can be stored in a shared workspace with permission controls and version history, enabling real-time or asynchronous collaboration across team members.
What export formats are supported?
Diagrams can be exported as SVG, PNG, or PDF, and can also be embedded in documents or presentations. The tool also supports lightweight diagram data export for interoperability.
Is there an offline mode?
The tool operates in a browser and relies on online storage for collaboration and persistence. An offline mode is not provided, and local persistence is limited to browser storage in some environments.

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