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Developer Diagram Studio

Design system architecture, sequence lifecycles, flowcharts, ER diagrams, and Mermaid code in one unified workspace.

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Create a Diagram

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Sequence Diagram

Lifelines, sync/async messages, return calls, activations, and notes.

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Flowchart Maker

Process logic, decision diamonds, branch conditions, and algorithms.

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Architecture Diagram

Cloud stacks, microservices, caches, event buses, and network VPCs.

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ER Diagram

Relational database schemas, table columns, PK/FK, and 1:N relations.

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UML Class Diagram

Object models, interfaces, methods, visibility indicators, and inheritance.

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Mermaid Editor

Live Mermaid.js code editor with vector preview and instant export.

Start From a Template

My Saved Diagrams

UML diagrams are designed locally in your browser with zero telemetry or tracking.

UML Class Diagram Maker — Object-Oriented Class Designer

Model object-oriented software architectures, design patterns, and class structures.

  • Runs in your browser
  • Free, no signup

Object-oriented system designs and architectural patterns (Factory, Strategy, Observer) are best documented using standard UML Class Diagrams.

The UML Class Diagram Maker provides structured class boxes, interfaces, visibility indicators (+ public, - private, # protected), typed methods, and inheritance/realization links.

How to use this tool

  1. Add classes or interfaces to the canvas from the left palette.
  2. Specify member attributes and methods with visibility prefixes (+, -, #).
  3. Connect classes with inheritance (extends) or realization (implements) connectors.
  4. Export to SVG, PNG, or standard Mermaid classDiagram syntax.

Frequently asked questions

How are visibility indicators represented?

Standard UML visibility notation is supported: + for public, - for private, and # for protected members.

Can I model abstract classes and interfaces?

Yes. Stereotypes such as <<interface>> and <<abstract>> can be applied to any class node.

Can I export to Mermaid class diagrams?

Yes. Click "Source Code" to view and copy standard Mermaid classDiagram syntax.

Diagram Studio

Professional diagramming workspace for Sequence, Flowchart, Cloud Architecture, ER, Class, and Mermaid diagrams.Use tool

Sequence Diagram Maker

Design synchronous, asynchronous, and return calls with automatic lifelines, message ordering, and Mermaid sync.Use tool

ER Diagram Maker

Model relational database schemas, tables, primary/foreign keys, and 1:N or M:N relationships.Use tool

Flowchart Maker

Create intuitive process flowcharts, decision trees, and workflow algorithms with smart connectors.Use tool