# For Developers

While `mdbook` is mainly used as a command line tool, you can also import the underlying library directly and use that to manage a book. It also has a fairly flexible plugin mechanism, allowing you to create your own custom tooling and consumers (often referred to as backends) if you need to do some analysis of the book or render it in a different format.

The For Developers chapters are here to show you the more advanced usage of `mdbook`.

The two main ways a developer can hook into the book’s build process is via,

- Preprocessors
- Alternative Backends

## The Build Process

The process of rendering a book project goes through several steps.

1. Load the book
   - Parse the `book.toml`, falling back to the default `Config` if it doesn’t exist
   - Load the book chapters into memory
   - Discover which preprocessors/backends should be used
2. For each backend:
   1. Run all the preprocessors.
   2. Call the backend to render the processed result.

## Using `mdbook` as a Library

The `mdbook` binary is just a wrapper around the `mdbook` crate, exposing its functionality as a command-line program. As such it is quite easy to create your own programs which use `mdbook` internally, adding your own functionality (e.g. a custom preprocessor) or tweaking the build process.

The easiest way to find out how to use the `mdbook` crate is by looking at the API Docs. The top level documentation explains how one would use the `MDBook` type to load and build a book, while the config module gives a good explanation on the configuration system.