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Describe your system in plain text and generate UML class diagrams, sequence diagrams, ER diagrams, flowcharts, and use-case diagrams instantly with a live Mermaid preview. Export as SVG or PNG. Free, no login required.
Quick Answer
What is a UML diagram generator?
A UML diagram generator converts plain-text descriptions or code into standardized Unified Modeling Language diagrams — including class diagrams, sequence diagrams, and ER diagrams — used in software architecture and design.
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What is a UML diagram and how do I create one for free?
Who Uses This Tool?
Software Engineers
Design system architecture, plan APIs, and document code structure with class and sequence diagrams.
System Architects
Map out infrastructure, database schemas, and microservice interactions using ER and flowchart diagrams.
Students & Educators
Learn UML notation, complete assignments, and visualize algorithms with ready-to-use templates.
Project Managers
Plan sprints with Gantt charts, track workflows, and communicate requirements with use case diagrams.
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Frequently Asked Questions
What is a UML diagram?▼
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Frequently Asked Questions
The tool generates class diagrams, sequence diagrams, entity-relationship (ER) diagrams, use-case diagrams, flowcharts, and activity diagrams using Mermaid.js syntax with a live preview. Describe your system in plain text and the diagram renders instantly.
No. You can describe your system or process in plain English and the AI will generate the correct Mermaid diagram code for you. You can also edit the Mermaid code directly in the editor if you want fine-grained control over the output.
UML (Unified Modeling Language) diagrams are standardized visual representations of software architecture and system design. Class diagrams show object relationships, sequence diagrams show method call flows, and ER diagrams show database schema — all essential for planning and documenting software projects.
Yes. You can export the diagram as an SVG or PNG image for use in documentation, presentations, README files, or design specs. The Mermaid code can also be copied and dropped into any Mermaid-compatible tool like GitHub, Notion, or Confluence.
Yes, it is completely free to use with no account, subscription, or API key required. Generate unlimited UML diagrams directly in your browser with no data sent to external servers.
Who Uses This UML Generator
Quickly prototype system designs with class and sequence diagrams before writing a line of code. Use live Mermaid preview to iterate on architecture in minutes and embed diagrams directly in ADRs and design docs.
Generate ER diagrams for database schema planning or sequence diagrams to document API call flows between microservices — ideal for onboarding new team members or reviewing complex integrations.
Complete UML assignments faster by describing your system in plain English and letting the AI generate properly formatted class and use-case diagrams. Export as PNG for inclusion in reports and presentations.
Create clear, professional system diagrams for product specs, API documentation, and onboarding guides without relying on a developer to draw them — no Visio or Lucidchart subscription needed.