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Mermaid vs PlantUML: catalog facts
Mermaid	PlantUML
Free Free and open source under the MIT licence.	Free Free and open source under the GPL.
Web, Command line	Windows, macOS, Linux, Web, Command line
Diagrams are plain text, so they diff and review like code Rendered natively by GitHub, GitLab and most documentation generators	Covers far more diagram types than most text-based tools Integrations for nearly every editor, wiki and documentation system
Layout is automatic, so fine control over positioning is limited Complex diagrams become hard to read in source form	Requires Java and, for some diagram types, Graphviz The syntax is inconsistent between diagram types
Web application, Downloadable app	Downloadable app, Web application
Open source	Open source
License: MIT	License: GPL-3.0
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 22, 2026

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