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npm / @mermaid-js/mermaid-cli

@mermaid-js/mermaid-cli

What changed in @mermaid-js/mermaid-cli 11 to 12, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-21.

8 breaking4 new APIs and options5 behavior and defaults1 tooling2 fixes and other

See which of these apply to your code, ranked, in your agent:

npx @unstale/cli init

@unstale/cli 0.2.1 on npm

@mermaid-js/mermaid-cli 1217 changes

Breaking changes 8

  • Upgrading to Mermaid v12.0.0 changes the default diagram themes and layouts.

    12.0.0release notes

  • Replaced by the improved --size option.

    12.0.0release notes

  • Now only looks for locally installed NPM icon packs; use --iconPacksAndUrls with a full URL for CDN downloads.

    12.0.0release notes

  • Node.js v22.13 or later is required.

    12.0.0release notes

  • The option has been removed; PDFs are now fitted by default.

    12.0.0release notes

  • Puppeteer v25 or later is required.

    12.0.0release notes

  • Replaces --width and --height, sets the Puppeteer viewport, and tries to produce PNG files at the given resolution.

    12.0.0release notes

  • Replaced by the improved --size option.

    12.0.0release notes

New APIs and options 4

  • Use this option with a full URL to dynamically download an icon pack from a CDN.

    12.0.0release notes

  • Disables embedding fonts into SVG files.

    12.0.0release notes

  • Use --pdf-paper-format=Letter to return to the old PDF fitting behaviour.

    12.0.0release notes

  • Recursive and OpenSans fonts are now supported.

    12.0.0release notes

Behavior and default changes 4

Fixes and other changes 1

@mermaid-js/mermaid-cli 113 changes

Behavior and default changes 1

Tooling 1

  • The Dockerfile adds mmdc to PATH, making the command available without specifying its full path.

    11.17.0release notes

Fixes and other changes 1