You can configure the parameters for your book in the book.toml file.

Here is an example of what a book.toml file might look like:

title = "Example book"
author = "John Doe"
description = "The example book covers examples."

destination = "my-example-book"
additional-css = ["custom.css"]

Supported configuration options

It is important to note that any relative path specified in the in the configuration will always be taken relative from the root of the book where the configuration file is located.

General metadata

This is general information about your book.

  • title: The title of the book
  • authors: The author(s) of the book
  • description: A description for the book, which is added as meta information in the html <head> of each page
  • src: By default, the source directory is found in the directory named src directly under the root folder. But this is configurable with the src key in the configuration file.
  • build-dir: The directory to put the rendered book in. By default this is book/ in the book's root directory.


title = "Example book"
authors = ["John Doe", "Jane Doe"]
description = "The example book covers examples."
src = "my-src"  # the source files will be found in `root/my-src` instead of `root/src`
build-dir = "build"

HTML renderer options

The HTML renderer has a couple of options as well. All the options for the renderer need to be specified under the TOML table [output.html].

The following configuration options are available:

pub playpen: Playpen,
  • theme: mdBook comes with a default theme and all the resource files needed for it. But if this option is set, mdBook will selectively overwrite the theme files with the ones found in the specified folder.
  • curly-quotes: Convert straight quotes to curly quotes, except for those that occur in code blocks and code spans. Defaults to false.
  • google-analytics: If you use Google Analytics, this option lets you enable it by simply specifying your ID in the configuration file.
  • additional-css: If you need to slightly change the appearance of your book without overwriting the whole style, you can specify a set of stylesheets that will be loaded after the default ones where you can surgically change the style.
  • additional-js: If you need to add some behaviour to your book without removing the current behaviour, you can specify a set of javascript files that will be loaded alongside the default one.
  • playpen: A subtable for configuring various playpen settings.


title = "Example book"
authors = ["John Doe", "Jane Doe"]
description = "The example book covers examples."

theme = "my-theme"
curly-quotes = true
google-analytics = "123456"
additional-css = ["custom.css", "custom2.css"]
additional-js = ["custom.js"]

editor = "./path/to/editor"
editable = false

For Developers

If you are developing a plugin or alternate backend then whenever your code is called you will almost certainly be passed a reference to the book's Config. This can be treated roughly as a nested hashmap which lets you call methods like get() and get_mut() to get access to the config's contents.

By convention, plugin developers will have their settings as a subtable inside plugins (e.g. a link checker would put its settings in plugins.link_check) and backends should put their configuration under output, like the HTML renderer does in the previous examples.

As an example, some hypothetical random renderer would typically want to load its settings from the Config at the very start of its rendering process. The author can take advantage of serde to deserialize the generic toml::Value object retrieved from Config into a struct specific to its use case.

# #![allow(unused_variables)]
#fn main() {
#[derive(Debug, Deserialize, PartialEq)]
struct RandomOutput {
    foo: u32,
    bar: String,
    baz: Vec<bool>,

let src = r#"
foo = 5
bar = "Hello World"
baz = [true, true, false]

let book_config = Config::from_str(src)?; // usually passed in by mdbook
let random: Value = book_config.get("output.random").unwrap_or_default();
let got: RandomOutput = random.try_into()?;

assert_eq!(got, should_be);

if let Some(baz) = book_config.get_deserialized::<Vec<bool>>("output.random.baz") {
  println!("{:?}", baz); // prints [true, true, false]

  // do something interesting with baz

// start the rendering process