mermaid-filter is a pandoc filter that adds support for mermaid syntax diagrams in markdown.

Write your diagrams in fenced code blocks as usual like this:

~~~mermaid
sequenceDiagram
    Alice->>John: Hello John, how are you?
    John-->>Alice: Great!
~~~

and get this in rendered doc

1. npm install --global mermaid-filter
2. To convert your markdown file something.md into something.html, use pandoc -t html -F mermaid-filter -o something.html something.md

WINDOWS - you need mermaid-filter.cmd in the line above

Windows 8.1 - On windows 8.1, mermaid-filter.cmd fails - apparently due to change in how the CMD.exe works for subprocesses? - see this issue thread. You have to edit the globally installed mermaid-filter.cmd located in c:\users\<username>\AppData\Roaming\npm to use ~dp$PATH:0. Unfortunately, you will need to do this each time you install/update mermaid-filter since it overwrites the cmd file.

You have a couple of formatting options via attributes of the fenced code block to control the rendering

Note that to specify options in attribtues, you need to use the curly braces syntax and have the .mermaid class attached. Admittedly, this is uglier than the earlier syntax on top - but that's how Pandoc wants it.

// saves generated diagram in the img subfolder of the current working dir

```{.mermaid loc=img}
// Your diagram code here
```

You can also specify an ID to be applied to the rendered image. This may be useful to use pandoc-crossref or similar packages to reference your diagrams, for example:

```{.mermaid #fig:example}
// Your diagram code here
```

This text has a reference @fig:example which is automatically inserted.

The title attribute is set to fig: by if the id specified starts with fig:

(Note that pandoc-crossref will automatically find and use the caption= option. Also note that the order of applying the filters matters - you must apply mermaid-filter before pandoc-crossref so that pandoc-crossref can find the images.)

Mermaid cli allows you to specify additional options in a json configuration file and a css file. mermaid-filter will look in the current working directory for .mermaid-config.json and .mermaid.css and if found, pass them in to mermaid cli.

Puppeteer Configuration - mermaid-filter will look in the current working directory for a .puppeteer.json and pass it on to mermaid cli (-p option of mmdc)if found