UML diagram tools
Pick a keyword-specific tool. Each page includes a live PlantUML editor plus a focused guide so you can create and learn in one place.
Structural UML
Show what the system is made of: classes, objects, components, packages, and deployment.
- Class Diagram MakerBuild a UML class diagram in your browser. Start from the template, rename types to match your domain, and export when the structure is clear.
- Object Diagram MakerDraw an object diagram when you need a snapshot of instances, not just types. Start from the template, fill in example values, and export when the scenario is obvious to your readers.
- Component Diagram MakerShow how larger software pieces depend on each other. Start from the template, rename components to match your system, and export for architecture notes.
- Package Diagram MakerMap packages and dependency direction so illegal imports show up early. Adapt the layered starter to your module names, then export when the rules look right.
- Deployment Diagram MakerDocument where software runs: hosts, containers, artifacts, and communication paths. Rename the starter nodes to match your environment, then export for ops reviews.
- Composite Structure Diagram MakerModel the inside of a complex class or component when a black-box view is not enough. Adapt the starter parts to your design, then export for detailed notes.
- Profile Diagram MakerCreate a UML profile when your team needs shared stereotypes and tagged values beyond stock UML. Start from the template and document only the extensions you will enforce.
Behavioral UML
Show what happens over time: interactions, workflows, use cases, and state changes.
- Sequence Diagram MakerDraw a sequence diagram for auth flows, service calls, and feature interactions. Start from the template, keep one happy path clear, then add error branches if needed.
- API Sequence Diagram MakerDocument an API call path with a sequence diagram: client, gateway, services, and status codes that matter. Adapt the starter hops to your endpoint, then export for specs.
- Activity Diagram MakerMap a workflow with actions, decisions, and end states. Start from the template, rename steps to match your process, and export when the path is clear.
- Use Case Diagram MakerShow who uses the system and which goals they pursue. Start from the template, keep use cases at goal level, and export for requirements workshops.
- State Diagram MakerModel a lifecycle with states and transitions. Ideal for order status, document review, and device modes. Adapt the starter, then export when every transition is intentional.
- Communication Diagram MakerUse a communication diagram when structural links matter as much as message order. Start from the template, number messages clearly, and export for design notes.
- Timing Diagram MakerPlot state or condition against time when duration and overlap matter more than a simple message list. Adjust the starter timeline, then export for timing talks.
- Interaction Overview Diagram MakerSketch a map of several interactions when one sequence diagram would be too dense. Adapt the starter flows, then point readers to detailed sequence pages.
PlantUML Editor
Write PlantUML in the browser with live preview and export.
Code-focused
Class diagrams tuned for Java and Python codebases.
- Java Class Diagram GeneratorProduce a class diagram for Java-oriented models: classes, interfaces, and inheritance. Adapt the starter to your packages, then export for README or design review.
- Python Class Diagram GeneratorBuild a class diagram for Python services, models, and dataclasses. Align names with your modules, then export for docs or onboarding.