Free Class Diagram Maker Online — No Signup Required
Class Diagram Maker helps you Draft Mermaid-compatible UML class diagrams with a browser-based editor — visualize OOP architecture — free, in 2026, without leaving the browser. It is built for developers, QA engineers, and technical writers, so you can format, validate, transform, or inspect structured technical data with a fast public URL, clear output, and a workflow that stays focused on the task instead of setup.
Free Class Diagram Maker — UML, Mermaid & SVG Export Online
Quick Answer
What are the main components of a UML class diagram?
A UML class diagram has three main components: (1) Classes — boxes divided into three sections: class name (top), attributes (middle), and methods (bottom); (2) Relationships — inheritance (solid line + hollow arrow), composition (filled diamond), aggregation (open diamond), association (solid line), dependency (dashed arrow), and realization (dashed + hollow arrow); (3) Multiplicity — numbers on relationship ends showing cardinality (1, 0..*, 1..n). Use this tool to draw and export class diagrams as SVG or PNG.
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What is Class Diagram Maker?
Class Diagram Maker is a developer productivity tool that lets you Draft Mermaid-compatible UML class diagrams with a browser-based editor — visualize OOP architecture directly in your browser. The interactive workspace above is the main interface — paste, upload, or configure your input, then copy or download the result. Nothing is sent to a remote server when the operation can run locally.
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Class Diagram Maker FAQs
Quick answers about the workflow, privacy, and where this tool fits in a broader job.
What does Class Diagram Maker do?
Class Diagram Maker lets you Draft Mermaid-compatible UML class diagrams with a browser-based editor — visualize OOP architecture.
Is this tool free, and is there a sign-up?
Yes — every tool on this site is free to use with no account required and no usage cap.
Is my data uploaded to a server?
When the operation can run locally in the browser, nothing is uploaded. A small number of tools call a public API for data they cannot fetch client-side; those pages say so explicitly.
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