Extend & Customize

Asciidoctor provides a default stylesheet and built-in converters so you can quickly process and convert your document, but it also lets you use custom stylesheets and converters. The Asciidoctor project includes alternative stylesheet themes from the stylesheet factory and specialized converters.
You can also create your own themes and converters.

Asciidoctor is highly customizable and has different levels of customization.

Built-in attributes: Asciidoctor has built-in document attributes that can be used to control the output. For instance, you can change the "Table Of Contents" location by using the toc attribute.
The Asciidoctor User Manual describes every built-in attributes that you can use.
Stylesheets: As mentioned above, Asciidoctor provided a default stylesheet but you can apply an alternative theme.
You can also create your own themes.
Docinfo files: You can add custom content to the head or footer of an output document using docinfo files. Docinfo files are useful for injecting auxiliary metadata, stylesheet, and script information into the output not added by the converter.
Template converter: A template converter is an implementation that uses templates to convert each block from a parsed AsciiDoc document tree to the output format.
Extensions: Asciidoctor provides an extension API that offers a list of extension points that open up the language to new use cases.
Custom converter: A custom converter is a specific implementation provided by the user that extends the Asciidoctor.Converter class.