mermaid-cli

This is a command-line interface (CLI) for mermaid. It takes a mermaid definition file as input and generates an svg/png/pdf file as output.

Example Usage

Locate how to call the mmdc executable for your preferred method i.e. Docker, Yarn, NPM, global install, etc. Try these examples to get started quickly.

Convert Mermaid mmd Diagram File To SVG

mmdc -i input.mmd -o output.svg

Create A PNG With A Dark Theme And Transparent Background

mmdc -i input.mmd -o output.png -t dark -b transparent

Animating an SVG file with custom CSS

The --cssFile option can be used to inline some custom CSS.

Please see ./test-positive/flowchart1.css for an example of a CSS file that has animations.

Warning: If you want to override mermaid's themeCSS, we recommend instead adding {"themeCSS": "..."}) to your mermaid --configFile. You may also need to use !important to override mermiad's themeCSS.

Warning: Inline CSS files may be blocked by your browser, depending on the HTTP Content-Security-Policy header of the website that hosts your SVG.

mmdc --input test-positive/flowchart1.mmd --cssFile test-positive/flowchart1.css -o docs/animated-flowchart.svg

Example output: docs/animated-flowchart.svg

Transform a markdown file with mermaid diagrams

mmdc -i readme.template.md -o readme.md

This command transforms a markdown file itself. The mermaid-cli will find the mermaid diagrams, create SVG files from them and refer to those in the markdown output.

This:

### Some markdown
```mermaid
graph
   [....]
```

### Some more markdown
```mermaid
sequenceDiagram
   [....]
```

Becomes:

### Some markdown
![diagram](./readme-1.svg)

### Some more markdown
![diagram](./readme-2.svg)

Piping from stdin

You can easily pipe input from stdin. This example shows how to use a heredoc to send a diagram as stdin to mermaid-cli (mmdc).

cat << EOF  | mmdc
    graph TD
    A[Client] --> B[Load Balancer]
EOF

See All Available Options

mmdc -h

Use Docker:

docker pull minlag/mermaid-cli

or pull from Github Container Registry

docker pull ghcr.io/mermaid-js/mermaid-cli/mermaid-cli

or e.g. version 8.8.0

docker pull minlag/mermaid-cli:8.8.0

The container looks for input files in /data. So for example, if you have a diagram defined on your system in /path/to/diagrams/diagram.mmd, you can use the container to generate an SVG file as follows:

docker run -it -v /path/to/diagrams:/data minlag/mermaid-cli -i /data/diagram.mmd

Use Node.JS API

It's possible to call mermaid-cli via a Node.JS API. Please be aware that the NodeJS API is not covered by semver, as mermaid-cli follows mermaid's versioning.

import { run } from "@mermaid-js/mermaid-cli"

await run(
   "input.mmd", "output.svg", // {optional options},
)

Install locally

Some people are having issues installing this tool globally. Installing it locally is an alternative solution:

yarn add @mermaid-js/mermaid-cli
./node_modules/.bin/mmdc -h

Or use NPM:

npm install @mermaid-js/mermaid-cli
./node_modules/.bin/mmdc -h

Install globally

❗️ We do NOT recommend installing it globally because both YARN and NPM could fail to install a command-line tool globally properly due to weird permission issues. yarn global add @mermaid-js/mermaid-cli or npm install -g @mermaid-js/mermaid-cli

Install with brew

brew install mermaid-cli

Run with npx

npx is installed by default with NPM. It downloads and runs commands at the same time. To use Mermaid CLI with npx, you need to use the -p flag because the package name is different than the command it installs (mmdc). npx -p @mermaid-js/mermaid-cli mmdc -h

Known issues

1. Linux sandbox issue
2. Docker permission denied issue

For contributors

Contributions are welcome. See the contribution guide.