Design & practice system diagrams, right in your browser.
UMLy pairs a fast studio for Use Case, ER, Class, and Data Flow diagrams with interactive, auto-graded puzzles.
Four diagram types, one unified studio
Every diagram type includes dedicated nodes, relationship connectors, and starter templates.
Use Case Diagrams
Actors, system boundaries, mandatory «include», optional «extend», and generalizations.
ER Diagrams
Entities, primary & foreign keys, weak entities, and crow’s foot cardinality.
Class Diagrams
Classes, interfaces, enums, attributes, methods, realization, and composition.
Data Flow Diagrams
External entities, numbered processes, data stores, and directional data flows.
Snap-to-grid canvas, keyboard shortcuts, undo/redo history, and starter templates with no account required.
19 interactive challenges across Beginner, Easy, Intermediate, and Advanced tiers with instant diagnostics.
Drafts persist in your browser automatically. Export crisp PNG, SVG, or JSON files in one click.
Ready to model your next system?
Jump straight into the workspace or test your skills with Level 1.