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Mermaid vs WebSequenceDiagrams: catalog facts
Mermaid	WebSequenceDiagrams
Free Free and open source under the MIT licence.	Free Described on its site as a free online tool.
Web, Command line	Web
Diagrams are plain text, so they diff and review like code Rendered natively by GitHub, GitLab and most documentation generators	Diagrams are written as plain text instead of drawn by hand Runs in the browser with nothing to install
Layout is automatic, so fine control over positioning is limited Complex diagrams become hard to read in source form	Only draws sequence diagrams Little public detail on export options and paid features
Web application, Downloadable app	Web application
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	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked October 2, 2026

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