Express middleware to serve markdown files as HTML

Usage no npm install needed!

<script type="module">
  import expressMd from '';



Build Status npm

Express middleware to serve markdown files as HTML


  • Handles Github-Flavored Markdown
  • Per-directory template support
  • In-memory caching
  • Handle requests for an entire site, or just a subdirectory
  • Pass variables to HTML templates using font-matter or server side vars
  • Defaults to beautifully clean Github look & feel if no template provided


npm install express-md --save


var express = require('express');
var expressMd = require('express-md');
var port = 3000;

var app = express();

// create an instance of express-md with custom options
var mdRouter = expressMd({

  // serve markdown files from `docs` directory
  dir: __dirname + '/docs',

  // serve requests from root of the site
  url: '/',

  // variables to replace {{{ varName }}} in markdown files
  vars: {
    message: 'Hello World!'

// add as express middleware

// start the server
app.listen(port, function () {
  console.log(expressMd.version + ' listening on port ' + port);

express-md options

You can configure express-md using the following options:

Option Description Default
dir Directory where markdown files are located
url URL from which markdown files should be served
extensions Markdown files with these extensions will be served ['.md', '.mdown']
passthrough Files with these extensions will be served as-is ['.css', '.png', '.jpg', '.jpeg', '.js']
headers Add additional HTTP headers
cache Override the caching subsystem. To disable caching, set this to false in-memory cache
watch Automatically reload files changes in dir false
ignore Request paths to ignore (supports strings and RegExp)
vars Variables to replace {{{ variableName }}} in markdown files

Mapping URLs to Markdown files

Place Markdown files with the extensions .md or .mdown in your docs directory. (You can override these file extensions; see below for details.) Organize the directory any way you like, with any number of subdirectories.

Each directory can have an (or index.mdown) file that will be served if the user requests the directory name.


A template.html file, if present in the same directory as a Markdown document, will be used to format that document. You can have multiple templates: express-md will search parent directories up the directory tree to find the nearest template.html and use that.

This allows you to have a default template, and override with custom templates in each subdirectory.

Template syntax

{{{ markdown }}}

In template.html, the text {{{ markdown }}} will be replaced by the HTML that was rendered from the Markdown document.

{{{ variableName }}}

You can specify placeholders in your HTML template using {{{ variableName }}} variables can be passed in using the vars option above, or using YAML font-matter within markdown files.

title: Barcode Scanner App
description: Orca Scan is a mobile barcode scanning app ...


Here is a quick example of how express-md resolves templates.


    <meta charset="utf-8">
    <title>{{{ title }}}</title>
    {{{ markdown }}}
    {{{ message }}}

Directory structure

For this example, assume the following directory structure:

├── template.html
└── api/
    ├── template.html
    └── v1.0/

The file docs/ is served using the template file docs/template.html.

The file docs/api/ would be served using the template file docs/api/template.html.

The file docs/api/v1.0/ is in a directory that does not have a template file. In this case, express-md will search up the directory tree until it finds a template. This file would be served using the template file docs/api/template.html. If express-md is unable to find a template, it will be served as a bare-bones HTML file which is styled to match Github readme.


Given the directory structure shown above, a request for http://localhost:3000/ would return docs/ (converted to HTML, of course).

File extensions are handled automatically. In this example, the README file can be requested as http://localhost:3000/README or http://localhost:3000/

Likewise, the api/ file can be requested as http://localhost:3000/api/, http://localhost:3000/api/, or even http://localhost:3000/api/index.

Error Documents

When an HTTP error occurs, express-md will look for a document matching the error number, using the same logic that is used to find templates. Currently only 404 errors are supported this way.

For example, to have a custom 404 error page, create a file. It will be converted to HTML and served using template.html just like any other Markdown file would be.

Like templates, you can have custom error documents in each subdirectory and express-md will use the nearest one when serving an error.


Q: How do I add a Cache-Control header ?

Use the headers option:

var middleware = expressMd({
  headers: {'Cache-Control': 'public,max-age=3600'},
  // other options…

Q: I've updated one of my markdown docs, but is still showing the old version

The old version of the document is cached, either by express-md or by your web browser. If you used a Cache-Control header, the document may be cached by your web browser. Hit F5 (or Cmd-R, or Ctrl-R) a couple of times to refresh.

If you still see the old document, then it’s been cached by express-md. Your options are:

  • restart express-md
  • disable server-side caching by passing false as the cache option
  • use the watch to force express-md to automatically notice any changes

Q: How does the cache work?

express-md aggressively caches the rendered, HTML form of your documents. The first time a document is requested, express-md has to read it from disk (along with any template) and render it to HTML. On subsequent requests for the same document, it will be served from cache, which should be extremely fast. In addition, requests that result in a 404 error are cached, so once express-md searches for a document and doesn’t find it, it won’t waste time looking for that document again.

By default, once a document is cached, express-md will never re-read that document; the cached version will always be served until you reload the server. You have the option to disable caching by passing false as the cache option.

If you enable the experimental watch option, the cache is emptied every time a change is detected in your docs directory or any of its subdirectories. Because it may be resource-intensive, this option is turned off by default. Enabling it when you have a large set of documents or subdirectories may exhaust available file handles. If you only have a few documents or subdirectories, feel free to try it out. Contributions to improve this feature are welcome.

Credit where it's due

This a refactor of the node-docserver project.


Licensed under MIT License