citeproc-java supports several output formats. The most common ones are "html" and "text" but you can also use "asciidoc", "fo", and "rtf".

Call the CSL processor’s setOutputFormat(String) method to set the desired format.

citeproc.setOutputFormat("html");
<div class="csl-bib-body">
  <div class="csl-entry">
    <div class="csl-left-margin">[1]</div>
    <div class="csl-right-inline">M. Krämer, “citeproc-java: A Citation Style
      Language (CSL) processor for Java,” 20-Nov-2016. [Online]. Available:
      http://michel-kraemer.github.io/citeproc-java/. [Accessed: 20-Nov-2016].
    </div>
  </div>
</div>
citeproc.setOutputFormat("text");
[1]M. Krämer, “citeproc-java: A Citation Style Language (CSL) processor for Java,” 20-Nov-2016. [Online]. Available: http://michel-kraemer.github.io/citeproc-java/. [Accessed: 20-Nov-2016].
citeproc.setOutputFormat("asciidoc");
[1] M. Krämer, ``citeproc-java: A Citation Style Language (CSL) processor for Java,'' 20-Nov-2016. [Online]. Available: http://michel-kraemer.github.io/citeproc-java/. [Accessed: 20-Nov-2016].
citeproc.setOutputFormat("fo");
<fo:block id="citeproc-java">
  <fo:table table-layout="fixed" width="100%">
    <fo:table-column column-number="1" column-width="2.5em"/>
    <fo:table-column column-number="2"
        column-width="proportional-column-width(1)"/>
    <fo:table-body>
      <fo:table-row>
        <fo:table-cell>
          <fo:block>[1]</fo:block>
        </fo:table-cell>
        <fo:table-cell>
          <fo:block>M. Krämer, “citeproc-java: A Citation Style Language
            (CSL) processor for Java,” 20-Nov-2016. [Online]. Available:
            http://michel-kraemer.github.io/citeproc-java/. [Accessed:
            20-Nov-2016].</fo:block>
        </fo:table-cell>
      </fo:table-row>
    </fo:table-body>
  </fo:table>
</fo:block>
citeproc.setOutputFormat("rtf");
{\rtf [1]\tab M. Kr\uc0\u228{}mer, \uc0\u8220{}citeproc-java: A Citation Style Language (CSL) processor for Java,\uc0\u8221{} 20-Nov-2016. [Online]. Available: http://michel-kraemer.github.io/citeproc-java/. [Accessed: 20-Nov-2016].
}