Ross Wintle

This plugin copies bookmarks from <a href="https://pinboard.in/" rel="nofollow ugc">pinboard.in</a> into a custom post type and the Pinboard tags into a custom taxonomy.
Note: This is not an official Pinboard plugin. If you have any problems please direct them to the WordPress support forums for this plugin.
This plugin:
<ul>
<li>runs automatically using either wp-cron or manually using <a href="https://wp-cli.org/" rel="nofollow ugc">wp-cli</a></li>
<li>uses the official Pinboard API (you will need your API key)</li>
<li>obeys the API’s rate limits</li>
<li>allows you to choose an author for synced pins</li>
<li>updates pins in pinboard that have been updated (I think!) but will not remove pins that have been deleted</li>
<li>provides a Gutenberg/block editor block for display a list of pins created between two specified dates</li>
</ul>
Note that this plugin does a one-way sync from Pinboard to your WordPress install. You can add your own bookmarks in WordPress but they will not be added to Pinboard.
<h4>Instructions</h4>
Once you have installed the plugin you will need to go to Settings -> Pinboard Sync and enter your API key 
(you can get this from your <a href="https://pinboard.in/settings/password" rel="nofollow ugc">Pinboard password settings screen</a>)
If you want to do automatic sync then you can then also turn on the Auto-sync option.
If you have a lot of pins in Pinboard then it is not recommended that you turn on auto-sync right away as this will probably time out or do bad things.
If you are able then the recommended method for doing a large initial import is to use the bundled wp-cli command: <code>wp-cli sync-pinboard</code>
<h4>WP-CLI command</h4>
If you can use <a href="https://wp-cli.org/" rel="nofollow ugc">WP-CLI</a> then you can make use of the <code>wp-cli sync-pinboard</code> command to 
do an import from Pinboard. This works particularly well for large first-time imports before you enable the automatic sync. But you could also use the system cron to run this command instead of WP cron.
<h4>Wish list / Roadmap</h4>
Things I have in mind for future development:
<ul>
<li>A shortcode for outputting lists of pins</li>
<li>Ability to only import a specified tag</li>
<li>(DONE) A Gutenberg block for displaying pins</li>
<li>Option in wp-cli command to allow re-import of all pins</li>
<li>Better front-end validation in admin screens and meta boxes</li>
<li>Better error logging, and logging in general, including WP-CLI-specific output</li>
<li>Better intial automated sync (over multiple cron runs)</li>
</ul>

Sync Pinboard

Works as it says it does. It was lacking a couple features I needed, but I reported them on github and Ross responded very quickly and was very helpful!

Pretty Good

Copies bookmarks from pinboard.in into a custom post type.

Josh Stauffer

Adds a shortcode to display Pinboard.in bookmarks in your content, widgets, or templates. Public feeds can be filtered by usernames or tags.
<h4>URL Patterns</h4>
The URL patterns for public bookmarks look like this:
<ul>
<li>https://pinboard.in/u:username/</li>
<li>https://pinboard.in/t:tag/</li>
<li>https://pinboard.in/recent/</li>
<li>https://pinboard.in/popular/</li>
</ul>
You can filter bookmarks by combining a username with tags:
<ul>
<li>https://pinboard.in/u:username/t:tag1/t:tag2/</li>
</ul>
You can filter bookmarks by up to three tags:
<ul>
<li>https://pinboard.in/t:tag1/t:tag2/t:tag3/</li>
</ul>
Please note that the URL must begin with <code>https://pinboard.in/</code>.
<h4>Usage Examples</h4>
Basic Example:
<pre><code>[wp_pinboard]https://pinboard.in/u:username/[/wp_pinboard]
</code></pre>
Advanced Example:
<ul>
<li>description: Whether to show of hide the description of the bookmark. Default ‘show’.</li>
<li>tags: Whether to show of hide the tags of the bookmark. Default ‘show’.</li>
<li>date: Whether to show of hide the date of the bookmark. Default ‘show’.</li>
<li>user: Whether to show of hide the username of the bookmark. Default ‘show’.</li>
<li>count: The number of bookmarks to display (max: 400). Default 20.</li>
<li>orderby: How to sort the bookmarks. Accepts ‘title’, ‘date’, or ‘random’. Default ‘date’. 
[wp_pinboard description=”show” tags=”show” user=”show” date=”show” count=”20″ orderby=”date”]https://pinboard.in/u:username/[/wp_pinboard]</li>
</ul>
Text Widget Example:
You can print bookmarks using a text widget like so: 
 [wp_pinboard]https://pinboard.in/u:username/[/wp_pinboard]
Template Example:
You can also print bookmarks directly in a template like so:

WP Pinboard

Adds a shortcode to display Pinboard.in bookmarks in your content, widgets, or templates. Public feeds can be filtered by usernames or tags.

Sync Pinboard vs WP Pinboard