pyuml2svg 0.4.61

Pure Python UML class diagram generator that renders SVG without dependencies.

pyuml2svg

pyuml2svg is a pure-Python library that generates UML class diagrams as SVG with no external dependencies.
It performs its own layout, places labels, draws canonical UML relationship arrows, and includes interactive collapse/expand controls directly in the SVG.

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Features

• Zero dependencies — pure Python + SVG
• Automatic portrait DAG layout
• Collision-aware edge labels
• Canonical UML markers (inheritance, composition, aggregation, etc.)
• Interactive collapse/expand of class hierarchies
• Disconnected-class highlighting
• Packaged CSS and JavaScript assets (no external files required)

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Installation

pip install pyuml2svg

Quick example

from pyuml2svg import UMLClass, UMLRelation, render_svg_string

classes = [
    UMLClass("Animal"),
    UMLClass("Dog"),
    UMLClass("Cat"),
    UMLClass("Spider"),
]

relations = [
    UMLRelation("Animal", "Dog", kind="inheritance"),
    UMLRelation("Animal", "Cat", kind="directed-association"),
    UMLRelation("Animal", "Spider"),
]

svg = render_svg_string(classes, relations)
with open("diagram.svg", "w", encoding="utf-8") as f:
    f.write(svg)

Open diagram.svg in any browser.

UML Relationship types

Supported kind values:

• inheritance
• realization
• composition
• aggregation
• dependency
• directed-association
• association
• link (plain line)

NB. Some of these are still WIP.