Nitin Yawalkar

RDFa Breadcrumb provide links back to each previous page the user navigated through to get to the current page or – in hierarchical site structures – the parent pages of the current one.
It gives you a new template tag called <code>rdfa_breadcrumb()</code> that you can place anywhere in your template files. It has inbuilt RDFa content markup, so this will help Google to recognize and display the breadcrumbs on search results as well.
Check out the screenshots.

RDFa Breadcrumb

An easy template tag for showing a breadcrumb menu on your site and on google search results with built in RDFa Markup.

Marin Atanasov

Provides the theme and plugin developers an easy way to build and implement highly customizable breadcrumb functionality, specifically tailored to their needs. 
Supports a lot of filters and hooks, and is written in OOP style, giving developers full control over the breadcrumb trail items and appearance. 
This plugin can also be embedded in themes, instead of installing it as a WordPress plugin.
<h3>Configuration</h3>
The most basic way to insert Carbon Breadcrumbs in your theme code is:
<pre><code><?php Carbon_Breadcrumb_Trail::output(); ?>
</code></pre>
If you want to specify various breadcrumb rendering options, you can specify them in an array, like this:
<pre><code><?php
Carbon_Breadcrumb_Trail::output(array(
 'glue' => ' &gt; ', // glue between breadcrumb items
 'link_before' => '',
 'link_after' => '',
 'wrapper_before' => '',
 'wrapper_after' => '',
 'title_before' => '',
 'title_after' => '',
 'min_items' => 2,
 'last_item_link' => true,
 'display_home_item' => true,
 'home_item_title' => __('Home', 'carbon_breadcrumbs'),
 'renderer' => 'Carbon_Breadcrumb_Trail_Renderer',
));
?>
</code></pre>
For additional configuration and developer documentation, you can visit the Github repository:
https://github.com/tyxla/carbon-breadcrumbs
<h3>Ideas and bug reports</h3>
Any ideas for new modules or any other additional functionality that users would benefit from are welcome.
If you have an idea for a new feature, or you want to report a bug, feel free to do it here in the Support tab, or you can do it at the Github repository of the project:
https://github.com/tyxla/carbon-breadcrumbs

Carbon Breadcrumbs

This remains the best breadcrumbs plugin I've used. In addition to its rich customization options, it provides developers with various easy ways to extend it.



The best breadcrumbs plugin I've used

This plugin has saved me quite some time.
Thanks to the numerous filters, you can adjust everything.
Respect <3

Very customizable

GREAT plugin, fantastic codebase: super clean & TESTED?! FTW!

Only downside is no schematagging out of the box :/. This is a pivotal SEO feature and I think this would greatly boost interest in your plugin.

Info: https://developers.google.com/search/docs/data-types/breadcrumbs#guidelines

Result should look like:

<ol itemscope itemtype="http://schema.org/BreadcrumbList">
 <li itemprop="itemListElement" itemscope
 itemtype="http://schema.org/ListItem">
 <a itemscope itemtype="http://schema.org/WebPage"
 itemprop="item" href="link.html">
 Crumb 1
 </a>
 <meta itemprop="position" content="1" />
/
 </li>
 <li itemprop="itemListElement" itemscope
 itemtype="http://schema.org/ListItem">
 <a itemscope itemtype="http://schema.org/WebPage"
 itemprop="item" href="link2.html">
 Crumb 2
 </a>
 <meta itemprop="position" content="2" />
 </li>
</ol>



Here's how I've shimmed it in:


<?php
 $breadcrumbs = new Carbon_Breadcrumb_Trail(array(
 'glue' => ' / ',
 'link_before' => '<li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem">',
 'link_after' => '</li>',
 'wrapper_before' => '<ol class="breadcrumbs" itemscope itemtype="http://schema.org/BreadcrumbList">',
 'wrapper_after' => '</ol>',
 'title_before' => '',
 'title_after' => '',
 ));

 $breadcrumbs->setup();
 echo $breadcrumbs->render(true); // WP_KSES strips itemprop, itemscope, etc, so bypassing!!!

 add_filter('carbon_breadcrumbs_item_attributes', _'breadcrumb_schematags', 10, 2);
 function breadcrumb_schematags($attributes, $item) {
 if (!is_array($attributes)) $attributes = array();
 $attributes['itemscope'] = null;
 $attributes['itemtype'] = 'http://schema.org/WebPage';
 $attributes['itemprop'] = 'item';
 return $attributes;
 }
 add_filter('carbon_breadcrumbs_item_output', 'breadcrumb_item_position', 10, 5);
 function breadcrumb_item_position($item_output, $item, $trail, $trail_renderer, $index){
 // Add Position
 $n = strrpos($item_output, '</li>');
 $item_output = substr($item_output, 0, $n) . '<meta itemprop="position" content="'. $index .'" />' . substr($item_output, $n);
 return $item_output;
 }

Really wonderful, well-thought code. wish there were schematags

A basic WordPress plugin for breadcrumbs with advanced capabilities for extending.

RDFa Breadcrumb vs Carbon Breadcrumbs