UML Diagram Tool
Class, sequence and use-case diagrams.
Try it: Document a small order domain
- Inspect the Order, Customer, OrderLine and Payable example.
- Replace attributes and method names with those in your own model.
- Review relationship labels and arrow types before exporting.
The editor draws diagrams; it does not compile UML, generate code or validate multiplicity and composition rules.
About UML Diagram Tool
UML is worth using for the parts people actually read: class structure and the relationships between types. The rest of the specification is rarely the point.
Class boxes, interfaces, inheritance and association connectors.
How UML Diagram Tool works in your browser
Class boxes carry the three standard compartments — name, attributes, operations — because that layout is what makes a class diagram scannable by anyone who has seen one before.
Relationships use their conventional notation: a hollow triangle for inheritance, plain lines for association. The distinction between "is a" and "has a" is the main thing a class diagram communicates, and drawing both as the same line loses it.
Drawing by hand rather than generating from code is deliberate here. A diagram of the design you intend is a different and often more useful document than a diagram of every class that currently exists.
When to use it
Designing a domain model before writing the code. Documenting the important types in a system for someone joining it. Explaining an inheritance hierarchy in a design review. Sketching a structure during a discussion without generating it from a codebase.
Frequently asked questions
Can I generate a diagram instead of drawing it?
Not on this canvas. Text to Diagram renders Mermaid class and sequence diagrams as a finished SVG or PNG; a diagram generated that way cannot be opened here for editing.
Which UML elements are supported?
Class boxes, interfaces, inheritance and association connectors — the parts of UML that get used in practice rather than the whole specification.
Is this full UML?
No, and deliberately so. It covers structural diagrams for documenting a design, not the complete notation with every diagram type.