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Mermaid vs StarUML: catalog facts
Mermaid	StarUML
Free Free and open source under the MIT licence.	Paid Commercial software; see the website for licence options.
Web, Command line	macOS
Diagrams are plain text, so they diff and review like code Rendered natively by GitHub, GitLab and most documentation generators	Covers most UML 2 diagram types Mixes UML, ERD, SysML, BPMN and more in one project
Layout is automatic, so fine control over positioning is limited Complex diagrams become hard to read in source form	Commercial licence Closed source
Web application, Downloadable app	Downloadable app
Open source	Closed source
License: MIT	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked October 1, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.